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Sunday, December 04, 2016

My Advice to Macroeconomists

Take two aspirins and call me in the morning (or maybe in 100 years).

As usual, I want to talk about crude empiricism vs microfoundations. I will argue that we should look at what has been tried in the past and whether it seems to have worked. This means I think we should not just keep our heads to down and to the grind-stone working on microeconomics until we have done it right and only then dare to attempt to advise policy makers. I have nothing against empirical microeocomic research, but I think this question is whether there are macroeconomists who have something useful to say even before the empirical microeconomics research program is completed.

I want to consider an example from another field of research -- aspirin. For all of human history, it has been reported that the roots of willows contain an analgesic. I do mean this literally -- it was reported by Herodotus. The pain killer was purified and named salycilic acid. There were three problems -- its mechanism of action (microfoundation) was completely mysterious, it caused ulcers, and it tasted horrible. The third problem was crucial, but it was solved roughly a century ago by the same reaction which gave us heroin Acetylation. Now we have access to Aceto Salyclic Acid AKA aspirin. Decades later, the mechanism was understood. Aspirin blocks synthesis of a number of molecules collectively called prostaglandins.

Now the research which explained aspirin's effect was worthwhile (well worth the real Nobel prize that was awarded). But there was no reason to refuse to take aspirin and suffer when its side effects were known but its mechanism was mysterious.

The micro (in this case nano) reasearch was useful. It made it possible to develop other non steroid anti-inflamatories. Importantly, it was understood that there were two related moelecules one of which caused inflamation, feaver and tenderness and the other of which caused the stomach and small intestine to releqase mucouse to protect themselves. This scientific research, followed by a massive controlled trial, lead to the availability of Vioxx and over 50,000 deaths.

I think the example is relevant for those who wonder if macroeconomists should stick with tried and true models (not of couse the academic literature dominatinng tried and false models) for a good long while.

Of course the old Keynesian models have their empirical failures. Such as ... uhm well not the stagflation of the 70s which was consistent with the expectations augmented Phillips curve used by the old Keynesians throughout the 1960s (starting with Samuelson and Solow 1960) but, well there was the failure to consider the hypothesis that there is Ricardian equivalence which is implied by almost all mroe modern models and supported by no data of which I am aware at all.

Well I am sure that there must have been something badly wrong with those models which were abandoned before I took my first economics course.

But seriously, I know of no difference between using those models and using aspirin in the 1960s.

Buchanan Smith and Krugman

Mark Buchanan and Noah Smith discuss what is wrong with Macroeconomics.

I think it is best to just click and read, but I particularly like two points

Buchanan: ... In 20-plus years writing about science, I've studied research in physics, biology, chemistry, psychology, anthropology and always found, after looking closely enough, that the models people use in these fields are usually well-motivated, make basic logical sense and get rejected if they don't fit the facts very well. Macroeconomics has been the one exception.


Smith: ... I think the biggest problem with macro is that models never get thrown in the trash. Researchers pump out theory paper after theory paper, most of which contradict each other. Sometimes we see a big, spectacular event like the 2008 crisis, which just couldn't happen in any of the popular, dominant, or Nobel-winning models. But then macroeconomists just pull some obscure 20-year-old paper off the shelf and say "Of course macro can explain this." Macro theory is sort of like a big collective effort to cover all the bases, not to find which models really work and which don't.

So if people criticize macro by saying to add this or that feature, they’ll do what you ask. But the papers will just sit on the shelves, and when it comes time to make policy, people pick and choose the theories that suit their preconceptions.

I do think that Smith makes a very important point. It is what he discussed (brilliantly do click this link) here "We will continue using this falsified theory to 'organize our thoughts'" and what I had in mind when I typed "benchmarks" (twice).

As Noah notes, the problem is fundamental. Macroeconomists act like scientists -- we develop hypotheses, infer testable predictions, test them, reject them and then come up with new models which fit the data which rejected the old hypothesis. But the rejected hypothesis becomes a model and then a benchmark model and many macroeconomists

"keep treating it as if it were true. So ... will continue to make highly questionable policy recommendations. The fact that this theory is such a simple, clear, well-understood tool - so good for "organizing our thinking", even if it doesn't match reality - will keep it in use long after its sell-by date.

On the other hand, i don't think macroeconomists have attempted to cover all bases. Smith fears that any data which contradict the benchmark model used to "organize our thinking" and to make confident policy recommenations can be reconciles with some off the shelf macro model which is put right back on the shelf as soon as people stop pointing at those data. He is right that this is what macroeonomists do. However, we have not covered all bases. I think it is easy to find stylized facts which are not consistent with any macro model in the literature. I think it is important that Noah knows lots of troublesome facts are just ignored. He wrote "Sometimes we see a big, spectacular event like the 2008 crisis, which just couldn't happen in any of the popular, dominant, or Nobel-winning models." The point is that the dodge is only required when the failure of all the popular models is "spectacular".

I really want to focus on a hint of an interesting debate between Smith and Krugman here in

Recently, more top macroeconomists are taking a hard look at the data to figure out how consumers and companies really behave -- for example, how businesses make decisions about setting prices and hiring or firing workers.


Note that this is the opposite of what a lot of macro critics are suggesting. Some, like Paul Krugman, advocate the use of very simple, old models, which are easy to use and interpret (especially in times of crisis). Others suggest tossing out the idea of individual decision-making as the foundation of macro models.

Noah concludes that Smith is right "The biggest challenge right now for macro is to move toward more realistic micro, using data as a guide. "

But there is a problem. Not all economists are macroeconomists. IO economists have tried to study how firms set prices and labor economists have tried to study labor demand. A practical form of Smith's proposal would be that macroeconomists should use the actual results of micro research and not microfound on decades old theories which have been rejected by the data. However, the actual proposal is that macroeconomists should first beat microeconomists in their own fields and then build macro models on the newly secured battlefield. Importantly Noah doesn't argue that there are perfectly good models of price setting in the empirical IO literature and macroeconomists just have to adopt them. Instead he proposes that we start to attempt to do empirical IO. But people have been working on that for decades. They aren't as numerous as macroeconomists, and they haven't made as little progress, but the history of that field doesn't suggest that the questions could be answered soon if they were just asked.

In constrast, Krugman's proposal is no good, because ... why ?

I wrote "an interesting debate," but not, I think, a fundamentally important debate. There is no reason why macroeconomists can't work on empirical microeconomics while also using old Keynesian models for forecasting and policy advice. Now one might argue that it would be better not to give advice until we have decent models based on empirical microeconomics. This would be true if macroeconomists forecasts were reliably worse than those of non-economists (indeed I am glad that Prescott who said that the then current problems were no big deal in early 2009 and Lucas who claimed to know that public investment couldn't cause increased nominal aggregate demand are not actively contributing to the policy debate).

It is not a sensible criticism of Krugman. I think it is clear that old Keynesian models are useful, beceause they give better forecasts and conditional forecasts than the judgment of non economists.

I have nothing against empirical micro research. Trying to understand price setting, hiring, firing and sayving decisions is worthwhile as pure social science in any case. But the idea that macroeconomists should be microeconomists for a while (how many decades ?) ignores that fact that policy makers are making horrible mistakes, and that (some) macroeconomists have reliably warned in advance that they are mistakes.

Thursday, November 17, 2016


I am an atheist, but I try to be open minded. Also, I am drunk out of my mind. So I am going to discuss what I think God Migh Conceivably Be if He/She or It Existed.

I do not claim that the evidence supports atheism. It is a faith, just as religions are faiths. Those with no faith are agnostics.

Howeever, I think it is proven beyond all doubt that there is no God who is Benevolent, Omnipotent, and Omniscient. The world is not ideal. St Augustine says there must be evil because there must be free will, because agents without free will lack something or other. I don't believe we have free will. But in any case, Hurricane Katrina sure didn't have free will. Things which clearly don't have free will act in a way which is morally wrong. Any God that might exist has no excuse for earthquakes and such.

For decades, I have lived off the fact that some behavioral economist put my name on 4 of their articles, so I must focus on this omniscience business. Could God be benevolent and omnipotent but ignorant and confused ? Give me a break. I don't believe in rational expectations any more than I believe in God, but the most idiotic and irrational deity has to understand that earthquakes hurt living things and that rocks don't enjoy the relief of their tension.

OK so we have to look at benevolence and omnipotence. Oddly, I actually believe in a benevolent God. I call him The moral Law (his friend call him morla). This is the embodiment of all that is good. Unfortunately, the moral law is not omnipotent or indeed potent at all. It tries to tell us what we should do, but can't get the words out because it (sadly) has no tongue (or lips or teeth or lungs or voice box).It sreams things which should be obvious (such as don't vote for Trump you moron) but its screams are silent.

Sometimes (such as on the morning of November 9 2016) I wonder if their might be two deities. The totally utterlessly powerless moral law and the Omipotent Nasty Bastard Who is Just Fucking with us. Now I must admit that This Divine Asshole has a Sense of Humor. If I wanted to Humiliate the USA, I wouldn't havde done such a Bang Up Fucking Impressive Job.

This means, that, if I had a religion, I would be Manichaen.

Their view as I understand it from Gibbon and just making it the fuck up is that there are two extemely powerful beings Ohrmazad (who forgives spelling errors) and Ahriman (who is gonna get me even if I spell His Name Right cause he got no clue about incentives).

Ohrmizad is very good. The Other Guy is a bad Guy Who created this vale of tears while Ohrmizad wasn't looking. This theology reconciles the idea that there is a benevolent deity with the plain fact that shit fucked up and bullshit.

In my view, the Creator of the Universe (who might be the One God if we are unlucky) has a Sick and Twisted Sense of Humor. I think that He created us to find the ultimate abyss of idiocy. Our purpose is to become so idiotic that it is not conceivable (even for an Omniscient but Really Nasty God) to think of anything more idiotic.

I fear that once we have achieved utter idiocy, the Universew will have serve His Purpose and cease to exist. So to those who ask me if I am worried about having a hangover tomorrow, I say, what makes you think there will be a tomorrow. Can you describe a possible idiocy which hasn't occurred some time since November 7 2016 ? If you can, I'll plan for the future. But I can't, so I will have another drink.

Wednesday, November 16, 2016

Marking My Beliefs To Market

One of the many admireable things which Brad DeLong does is to mark his beliefs to market. I decided to do a bit of that. I realize that one very hard step is to find the markable beliefs. I decided to google [prediction] and got a few (including that Kerry would win in 2004).

Usually I use the word to refuse to make a prediction (especially after 2004) but I found a few.

1) UK violent crime

Kevin Drum has written a lot about the lead causes crime hypothesis. I believe it was proposed by someone at the EPA in the 1990s a very few years after the peak of the US murder rate. I consider myself an early supporter (about as early as Drum even if much less industrious).

In April 2008, I predicted that the UK violent crime rate would peak some time around 2008

I just googled and found that it peaked in around 2006 or 2007

I'd say the prediction worked out pretty well.

2) TARP cost

Again and again, I predicted that the CBO forecast cost of TARP was higher than the expected cost of TARP and that the forecast would be reduced. I think the first time I did this was September 18 2010

Again and again I was right. The books were (roughly) closed with a reported non cost of over $15 billion of profit.

This predition worked out pretty well too.

3) PPIP cost

On a much more minor issue, I predicted that the Public Private investment Partnerships wouldn't coast the US government, and in particular the FDIC, much money. This is interesting mainly because I challenged Joe Stiglitz, Paul Krugman, and (I just learn) Jeff Sachs. The books have been closed. The Treasury made a positive return of $ 3.9 billion. The rate of return was vastly greater than the rate the Treasury pays. Even assuming the 3.9 was earned all at the end the return would be 3.9/18.6 after 5.5 years so an annual rate of 3.5% compared to the Treasury 5 year rate of oh around zero.

4) Hmm turns out I predicted that Marco Rubio would not be the GOP nominee.

5) Huh it seems I predicted that George Bush would offer to nominate Patrick Fitzgerald to the Supreme Court and that he did in fact do so. Either or both of my prediction and this alleged Fitzgerald e-mail might be jokes.

à 6) Effectiveness of Quantitative Easing. This is tricky, because while I actually became a tiny bit known as a skeptic (I was actually interviewed by a journalist once) I flinched and said Abenomics had worked. Also I tended to argue that QE based on purchases of risky assets would work better than QE based on purchases of long term bonds. I think my first foray into QE skepticism was this on February 26 2011 . See also this. But I tend to claim some success. I am pretty sure I was relatively skeptical of QE. There were critics who thought it would work too well and cause hyperinflation, but I am fairly sure I was fairly far out towards the most extreme position of saying it wouldn't have much effect. This not really stuck to prediction is working out rather well.

Marking My Beliefs To Market

One of the many admireable things which Brad DeLong does is to mark his beliefs to market. I decided to do a bit of that. I realize that one very hard step is to find the markable beliefs. I decided to google [prediction] and got a few (including that Kerry would win in 2004).

Usually I use the word to refuse to make a prediction (especially after 2004) but I found a few.

1) UK violent crime

Kevin Drum has written a lot about the lead causes crime hypothesis. I believe it was proposed by someone at the EPA in the 1990s a very few years after the peak of the US murder rate. I consider myself an early supporter (about as early as Drum even if much less industrious).

In April 2008, I predicted that the UK violent crime rate would peak some time around 2008

I just googled and found that it peaked in around 2006 or 2007

I'd say the prediction worked out pretty well.

2) TARP cost

Again and again, I predicted that the CBO forecast cost of TARP was higher than the expected cost of TARP and that the forecast would be reduced. I think the first time I did this was September 18 2010

Again and again I was right. The books were (roughly) closed with a reported non cost of over $15 billion of profit.

This predition worked out pretty well too.

3) PPIP cost

On a much more minor issue, I predicted that the Public Private investment Partnerships wouldn't coast the US government, and in particular the FDIC, much money. This is interesting mainly because I challenged Joe Stiglitz, Paul Krugman, and (I just learn) Jeff Sachs. The books have been closed. The Treasury made a positive return of $ 3.9 billion. The rate of return was vastly greater than the rate the Treasury pays. Even assuming the 3.9 was earned all at the end the return would be 3.9/18.6 after 5.5 years so an annual rate of 3.5% compared to the Treasury 5 year rate of oh around zero.

4) Hmm turns out I predicted that Marco Rubio would not be the GOP nominee.

5) Huh it seems I predicted that George Bush would offer to nominate Patrick Fitzgerald to the Supreme Court and that he did in fact do so. Either or both of my prediction and this alleged Fitzgerald e-mail might be jokes.

à 6) Effectiveness of Quantitative Easing. This is tricky, because while I actually became a tiny bit known as a skeptic (I was actually interviewed by a journalist once) I flinched and said Abenomics had worked. Also I tended to argue that QE based on purchases of risky assets would work better than QE based on purchases of long term bonds. I think my first foray into QE skepticism was this on February 26 2011 . See also this. But I tend to claim some success. I am pretty sure I was relatively skeptical of QE. There were critics who thought it would work too well and cause hyperinflation, but I am fairly sure I was fairly far out towards the most extreme position of saying it wouldn't have much effect. This not really stuck to prediction is working out rather well.

Sunday, November 13, 2016


John Podhoretz who wrote

"What if the tactical mistake we made in Iraq was that we didn't kill enough Sunnis in the early going to intimidate them and make them so afraid of us they would go along with anything? Wasn't the survival of Sunni men between the ages of 15 and 35 the reason there was an insurgency and the basic cause of the sectarian violence now?"[7]

John Podhoretz (July 25, 2006). "Too Nice to Win? Israel's Dilemma". New York Post. Retrieved April 7, 2007

Just tweeted "@robertwaldmann @jbarro I think you assume I'm a jerk, which basically means you're a jerk."

To assert is not necessarily to assume. I assert that someone who lamented the surviaval of Sunni men between the ages of 15 and 35 is a jerk. I don't think this assertion is a mere assumption. I don't think that my assertion that John Podhoretz is a jerk is evidence that I am a jerk.

I favor civility and oppose genocide, but, having been forced to choose between those two values by genocide advocate John Podhoretz, I sacrifice civility.

In any case aside from the fact that it is too kind to call an advocate of genocide a jerk, the original point was that J Barro tweeted the following @ "@jpodhoretz I don't think it's at all clear that Dems have settled on obstruct-and-deligitimize. "

My allegedly jerkish claim was that J Podhoretz responded to the election of Barack Obama by attempting to deligitimize Obama and by advocating obstruction.

Friday, November 11, 2016

The Washington Post's Brilliant (and Ruthless) Editorial Choice

Today the Washington Post opinion section demonstrated that The Wall Street Journal has employed a complete total idiot.

"Asra Q. Nomani is a former Wall Street Journal reporter and a co-founder of the Muslim Reform Movement. She can be found on Twitter at @AsraNomani."

Ms Nomani's explanation of why she voted for Trump begins

"I am a single mother who can’t afford health insurance under Obamacare. The president’s mortgage-loan modification program, “HOPE NOW,” didn’t help me."

Ms Nomani is a Muslim immigrant, Donald Trump refused to answer a question about whether Muslim non citizens should be allowed to enter the USA.

It is very clear that she voted against Clinton and didn't think much at all about the candidate whom she and tens of millions of others elected. I had thought that the Wall Street Journal news pages if not the opinion pages is excellent. But now I understand that they hired a reporter wh is totally incapable of practical rational thought.

I guess I will stick with the Washington Post and New York Times. So Fred Hiatt scored bigly.

Monday, October 31, 2016

Long Term Effects of Comeygate ?

I assume the reader is familiar with the furor related to the letter sent by FBI director James Comey to Rep. Joshua Chaffetz (Rep. Utah (in this case Rep. stands for reprensible)).

I am wondering about what effects it will have after November 8th. There has been a good bit of discussion of how anything including the words "e-mail" and "Clinton" is bad for Democrats. Many guess that Hillary Clinton will, nonetheless, be elected president (I stress that I have never made any prediction related to that possibility and have *not* jinxed anything). Some suggest that the nothing burger will affect down ballot elections.

I am wondering about the long term effects in the hypothetical case that Clinton becomes President (I make no prediction one way or the other regarding this eventuality). It is very clear and alarming that some of the people insanely dedicated to getting a Clinton are FBI agents. I guess this isn't really surprising.

I am wondering (and hoping) that the Clinton haters have gone too far. FBI director James Comey has been very widely denounced. For two days the story line has been "US government employees abuse their offices in their efforts to get Clinton). I think it is possible that the conventional wisdom will be that Clinton persecution is a serious national problem. I wonder if this might be very very useful to the hypothetical second President Clinton.

What Happened to the 4th amendment ?

The FBI now has a warrant to read e-mails sent and received by Huma Abedin which are stored on a laptop which she shared with Anthony Weiner.

Kevin Drum asks what took them so long and strongly suggests that someone at the FBI wanted to make sure that the investigation was opened and not closed before the election.

"If the FBI knew about these messages weeks ago, they could easily have gotten a warrant and begun looking at them."

I think it is clear that someone (not the director) at the FBI has deliberately used his or her position there to influence the election at the expense of the alleged public interest in investigating Abedin e-mails. I'd say this is a clear violation of the Hatch act and that after being fired, this person should be investigated for possible criminal liability.

But there is something which isn't clear at all to me.

I don't understand how that was possible let alone easy. I vaguely recall the phrase "probable cause": It doesn't seem to me that the fact that Huma Abedin uses e-mail is probable cause to believe a crime has been committed. Last I checked e-mail was not banned. The fact that they sought a warrant means the FBI agrees that they can't read the stuff on that hard disk which was written by Abedin or to Abedin without a warrant. How can they obtain probable cause to believe something about what was written without reading any of it ?

Comey said that the Abedin related data on the hard disk "appears to be pertinent": How can one describe the appearance of something when one is not allowed to look at it ?

I stress that among the things that Abedin may have written which the FBI must not read without a warrant is the following text ".gov". I don't think they can obtain any evidence that any of the e-mails is work related without a warrant. I also don't think the FBI should have been granted a warrant without presenting evidence that at least one of the e-mails is work related.

I see no way to reconcile the decision of some judge with the 4th amendment.

Needless to say, I am not a lawyer.

Orrin Kerr is a lawyer (and a conservative). His post is worth reading.

Saturday, October 29, 2016

Schadenfreude and the New York Times

I very much enjoyed the recent columns on the current status of conservatism by David Brooks and Ross Douthat. I don't have anything useful to write, because (as frustratingly usual) I have nothing useful to add to Paul Krugman's post. So I will write a useless post.

Briefly, Brooks and Douthat agree that Conservative's have lost their way

"Eventually a path for conservative intellectuals will open.

But for now we find ourselves in a dark wood, with the straight way lost." Ross Douthat

"Trump demagogy filled the void.

This is a sad story." David Brooks

I agree with Krugman that "both deserve credit for taking a critical look at their team."

I think there is now a consensus among the New York Times opinion staff. The two token conservatives just wrote that they agree with the rest of them. Note that "nytimes" appears in the three urls but the blog post nor either column includes the word "York". This shows the genuinely impressive elitist arrogance of the New York Times staff. All three present the current state of opinion among the New York Times opinion staff as the current state of informed opinion.

On Brooks I note only three things. First he really lead with his chin when he wrote

"I feel very lucky to ... The role models in front of us were people like ... Irving Kristol ..." and later " conservative opinion-meisters began to value politics over everything else." Did he really not know that Krugman would respond by typing "'the accounting deficiencies of government'" among other things ? Even sticking with the same nuclear family, he could have written "Gertrude Himmelfarb" instead of "Irving Kristol". Note that Brooks considers himself to be part of the conservative intellectual elite. I don't want to think what rhetorical errors he things non elite conservatives make.

Second Krugman referred to Brooks as "David" in his blog. I don't recall that happening before. I think it is an olive branch.

Finally Brooks wrote both "The very essence of conservatism is the belief that politics is a limited activity, and that the most important realms are pre-political: conscience, faith, culture, family and community. " This is extremely offensive (so no olive branch from me). That can only be the essence of conservatism if it is not shared by non conservatives. If Brooks's sentence means anything, it asserts that non conservatives think that politics is more important than "concience, faith, culture, family and community." That claim comes close to libel. Of course Brooks doesn't mean that. He doesn't mean anything. He correctly describes that vaguely related difference between non conservatives and conservatives later

For years, middle- and working-class Americans have been suffering from stagnant wages, meager opportunity, social isolation and household fragmentation. Shrouded in obsolete ideas from the Reagan years, conservatism had nothing to offer these people because it didn’t believe in using government as a tool for social good.

Believing or "not believing in using the government as a tool for social good" is the actual difference between non-conservatives and conservatives which Brooks incorrectly describes in his outrageous implied insult of non-conservatives. I don't think that it makes any sense to call Brooks a conservative -- he just plays one on TV. He can only claim to be conservative by dividing people into Leninists and "conservatives." I don't think he has ever even tried to explain how he can claim that, to name two examples, Paul Krugman and Hillary Clinton don't embrace his "essence of conservatism".

I think Brooks is reduced to justifying his claim to deserve to keep his excellent job with the following syllogism "conservative thinkers have something useful to contribute. I am a conservative thinker. Therefore I have something useful to contribute": I don't think he has (or can) present an argument for either of the first two claims in the syllogism. I don't think he's even trying anymore.

Douthat is marginally more interesting. He is very openly elitist: the frankness of "the pyramid that is modern American conservatism has always been misshapen, with a wide, squat base that tapers far too quickly at its peak.

The broad base is right-wing populism, in all its post-World War II varietals: Orange County Cold Warriors, “Silent Majority” hard hats, Southern evangelicals, Reagan Democrats, the Tea Party, the Trumpistas. The too-small peak is the right’s intellectual cadres," is bracing.

His column is based to a large extent on the words "populism" and "managerialism". He abuses both.

First he discusses only right wing populism. This makes it possible for him to identify populism with right wing populism and write "the toxic tendencies of populism, which were manifest in various hysterias long before Sean Hannity swooned for Donald Trump." leaving out the qualifier "right-wing". The claim is technically true. If it just so happens that all those hysterias were right wing it isn't necessary to note this fact. But Douthat should ask himself if he can think of analogous widespread left wing hysterias. I don't think they occurred. Not all 9-11 truthers support and are praised by Donald Trump. But those on the left are an isolated fringe. There are fairly large numbers of extremely angry leftists (black lives matter and occupy wall street) but their claims of fact are supported by overwhelming evidence and their policy proposals are reasonable. A solid majority of US adults have left of center populist views -- they support higher taxes on the rich and more generous entitlements. These people clearly have strong suspicions (for example that the GOP focuses mainly on serving its rich donors). But that belief is not paranoid hysteria. It is a fair summary of the available evidence. As noted by Krugman, neither Douthat nor Brooks even discuss the issue. I think that Douthat would have two separate problems. First, Krugman explains how conservative commentators could remain prominent even if they have nothing useful to say, but second, because the widespread but non hysterical egalitarian populist views demonstrate that populism isn't as prone to toxic tendencies as Douthat asserts.

I object more srongly to Douthat's use of "managerialism". First it is pretentious jargon -- Burnham wrote a long time ago and few people remember him. I think that Duthat should replace "managerial" with "informed". I think that is what he means. It is an insult to managers to call university professors "managerial" (n my experience, this is also true of professors of business management). Most managers in the USA are middle managers of private sector corporations. That's not the managerial class Douthat has in mind. He makes it clear that he means "three generations after Buckley and Burnham, the academy and the mass media are arguably more hostile to conservative ideas than ever, and the courts and the bureaucracy are trending in a similar direction." Note that somehow the mass media has been redefined to exclude Rush Limbaugh and Fox News). Note that senators, representatives, governors, and Kochs are not included among the managerial elite. He isn't referring to the powerful or the rich. Of course he is thinking of the New York Times opinion staff and complaining that he has lost all the water cooler debates for years. But he should at least try to define a large important group which is "more hostile to conservative ideas than ever."

I believe that group would be the people who know and deal with facts which don't concern them personally (everyone deals with facts in our ordinary lives). Basically, I think the problem noted by Douthat is that conservatives have lost all the debates in which arguments must be supported by facts or logic. He has decided to define the people who know the relevant facts (and are honest) as "the overclass" because defining knowledge as class is a way to discredit it.

I think it is possible to remove these problems by always adding "right wing" to "populism" and replacing "manager" with "subject matter expert" and "managerial" with "of subject matter experts". The insinuation that those who have rejected conservatism are acting as a class is a cheap rhetorical trick (and just another sign that, if you want a recent example of the typical defects of Marxist thought, you should read a contemporary conservative).

In his "to be sure" passages, Douthat writes some positive things about one conservative and some conservative thought. These assertions are completely unconvincing.

Consider the wonderful internal contradiction in "in reality political conservatism’s leaders — including high-minded figures like Paul Ryan — turned out to have no strategy save self-preservation." Douthat asserts that Ryan is "high-minded" and has "no strategy save self-preservation". He doesn't claim that Ryan used to be high-minded then changed. He doesn't admit that those who thought that Ryan was high minded were deceived by transparent flim flam. He admits that he and many others were totally wrong about Ryan but won't admit that Krugman and Jon Chait were right all along. I think that the absurd intellectual error can be eliminating by adding as single word replacing "high-minded" with " alledgedly high-minded". The extremely charitable might also accept "apparently high-minded".

Douthat also wrote

Partial revolutions there were. Free-market ideas were absorbed into the managerial consensus after the stagflation of the 1970s. The fall of Communism lent a retrospective luster to Reaganism within the foreign policy establishment. There was even a period in the 1990s — and again, briefly, after Sept. 11 — when a soft sort of social conservatism seemed to be making headway among Atlantic-reading, center-left mandarins.

I have noted that the claim that stagflation demonstrated any errors of earlier non-conservative economic thought is based entirely on lies. It is true that the boldly lying right managed to promote right wing economic ideas. The claim about "luster" is even farther from illustrating a claim in which evidence turned out to support conservative's claims. I am old enough to remember that, in the 70s and 80s the conservative position was that the USSR and communist movements were much stronger than non-conservatives admitted. It turns out that non-conservatives were totally wrong, because they came to close to agreeing with the claims of conservatives. I have no idea what "soft social conservatism" Douthat has in mind.

Thursday, October 27, 2016

Benchmark II

I wrote a post on Benchmarks which got some attention.

I defined a benchmark model as a model which we do not think is a useful approximation to reality but " which we wish to use only by contrasting it with models which we think might be useful approximations to the truth."

I'm not going to read my old post and might repeat things here.

I argued that the choice of benchmark models is not at all innocent and that economists' choice of benchmarks can affect economic outcomes.

My claim is that a chosen benchmark might give the incorrect impression of a consensus, and that non specialists are especially likely to mistake the choice of a benchmark for a scientific discovery.

I will discuss two examples of assumptions made just to benchmark which I think are dangerous. First most macroeconomists have agreed to treat technology as exogenous. I think this particular choice helps explain Paul Romer's extreme irritation with the profession. Second, most macroeconmists have agreed that long run forecasts are best made using a neoclassical model without frictions. This means that the macroeconomic discussion is about the optimal model of convergence to a given long run which is given by assumption and not analysis or evidence. This provoked Roger Farmer to be almost as harsh as Paul Romer (by the way reading that Farmer post is a much better use of your time than reading this post).

First I would like to use these two examples to describe benchmarking, that is to ask why assumptions may become conventional (almost universal) even if they are neither plausible a priori or supported by data.

It is obvious that technological progress is the product of human efforts and doesn't fall out of the sky (like genuinely exogenous meteors). There is a separate sub-field of macroeconomics called growth economomics which attempts to understand and explain the long run. The benchmark model used by business cycle macroeconomists (that is most macroeconomists) is based on the assumption that this literature reached it's epitome, zenith, optimum and telos with the Ramsey-Cass-Koopmans model in the 1960s (see above "irritation" and "Romer").

I think that it is standard to assume exogenous technology and convergence to a unique Ramsey-Cass-Koopmans balanced growth path for three reasons.

1) Business cycle macroeconomists want to focus on the business cycle. There is an agreement to divide the macroeconomic research program into growth theory and the rest of it. People who focus on the rest of it gain the ability to understand each other by agreeing to use the same model of long run growth. They (we ?) agree on Ramsey Cass Koopmans for the sake of discussion of topics other than long run growth.

2) It is almost impossible to model technological progress. If one can Understand how things are invented and predicting what will be invented, one had beter be an inventor than an economist. Here technological progress is exogenous to our models, because we don't think we can model it. So either we give up or treat it as given.

3) It is hard to evaluate models of the long run, because there is a shortage of non-overlapping long runs. The empirical literatures are very different with different data sets, techniques and necessary but not convincing assumptions. The long run evidence must all mostly concern events which occured long ago or far away. Even if economists were convinced that this evidence is relevant to first world macroeconomic policy makers, we wouldn't be able to convince the policy makers.

Now the three explanations of why we benchmark are three arguments for not taking those shared assumptions seriously. They are what we all say about things we don't think about, don't understand and don't observe.

Unfortunately, they are also the questions on which macroeconomists appear to agree. The assumption that technology is given is almost always made. It is almost always assumed that the long run expected values of (properly scaled) variables are unique and not affected by macroeconomic policy. This happens because macroeconomists do not want to talk about the causes of technological progress or the determinants of long run outcomes.

This means that (as stressed by Farmer) that natural rate hypothesis of unemployment is accepted by default. It is also assumed to be valid here in Rome where unemployment has been much higher in the past 4 decades than it was before.

More generally, it is generally assumed that macroeconomic policy can't affect the long run values of real variables. This means that macroeconmists tell politicians than far sighted statesmen will focus only on price stability, because the real variables will take care of themselves. This means that policians who don't trust themselves (or especially each other) will impose that exclusive focus as a rule.

So we have a European Central Bank with a single price stability mandate, and a Stability and "Growth" pact which forbids fiscal stimulus.

I think the effects of these policy choices have been horrible. I also think that at least part of the blame belongs to macroeconomists who wanted to focus on something else and neglected to warn policy makers that their agreements for the sake of argument weren't a scientific consensus.

Monday, October 10, 2016

Hillary Clinton's Tweet About Rape

Hillary Clinton tweeted

Hillary Clinton ✔ @HillaryClinton

Every survivor of sexual assault deserves to be heard, believed, and supported.

2:09 AM - 23 Nov 2015

This is evidence that human intelligence will be buried because it has created it's own grave digger -- Twitter. I will attempt a close reading of the tweet. I think it is generally miss-interpreted.

The widespread interpretation (sorry no links) is that everyone who claims to be a survivor or sexual assault deserves to be believed. This would be a crazy proposal. Without qualification that means deserves to be believed by police, prosecutors and jurors. This would give each of us the power to send each of us to prison for years whenever we pleased.

But that isn't what Clinton wrote. "survivor" is not the same as "person who claims to be a survivor". Taken literally, Clinton said that people who tell the truth deserve to be believed. This is a truism. It does not imply that it is humanly possible to provide every truth teller with the belief he or she deserves. We may honestly not know that a true claim is true.

Total literalism makes the statement a truism. The widespread intepretation which goes beyond the dictionay definitions of words makes it an insane proposal.

I think the literal interpretation is more plausible. It would make no sense to tweet "Everyone who accurately claims to be a survivor of sexual assault deserves to be believed" since that goes without saying. It would make sense to write "Everyone who accurately claims to be a survivor of sexual assault deserves to be heard, believed, and supported," because the support doesn't automatically and effortlessly follow from the belief.

I actually think that Clinton was presenting a goal knowing it can't be fully achieved. There is no way to believe every accurate claim of assault and disbelieve every inaccurate claim. We cant always know.

Trump's Lies about Hillary Clinton and Bill Clinton's Sexual Misconduct and Alleged Sexual Misconduct

Donald Trump went there (as we all knew he would eventually). After being caught on tape boasting about his sexual assaults, Trump claimed that he was lying (plausible) and that Bill Clinton actually did it (including rape). Together with the 22nd amendment will certainly prevent the re-re-election of Bill Clinton, but it doesn't seem to have much to do with the 2016 Presidential election. Trump regularly tries to claim that is accusations against Bill Clinton are relevant, because Hillary Clinton was a very nasty enabler who attached, shamed, humiliated and threatened the women with whom Bill Clinton conducted himself badly.

I have been concerned that reporters have reported that accusation against Hillary Clinton without writing whether it is supported by any evidence. I have also wondered if I missed something back in the 90s when I wasn't such a US political news addict. I have now concluded that Trump's accusations are completely unsupported by any evidence at all. It isn't surprising that Trump would make convenient claims of fact based on zero evidence. It isn't even surprising that journalists report slanderous claims without noting that they are false.

But, before going on, I must stress that I consider this another gross journalistic failure. I think reporters should have a rule that they just don't report accusations without independently chekcing the evidence. I do not think minimal journalistic standards are met when they quote Trump's accusations without any discussion of whether they are supported by any evidence. I am absolutely sure that many people are convinced that it is generally agreed that Hillary Clinton attacked some woman with whom Bill Clinton had sex or whom Bill Clinton harrassed. This is an accusation which I have read many times.

Only in the past day and only by deliberately looking have I found some fact checks. Trump claimed “Bill Clinton has actually abused women and Hillary has bullied, attacked, shamed and intimidated his victims.”. I know of no case in which he named the women whom he claimed were attacked by Clinton. I assume they are among the set of Monica Lewinsky, Paula Jones, Gennifer Flowers, Katharine Willey and Juanita Broaddrick. I know of no claims by Trump about the time or content of the alleged attacks, threats etc. I think a challenge for fact checkers is to add enough to the totally vague abstract accusations to make them checkable.

I will try to guess what Trump might have had in mind. Of course I don't really think he had any specific claim in mind, I think he just found it convenient to accuse Hillary Clinton.

1) This seems to be the closest to a hint of some evidence -- yesterday Juanita Broaddrick said that Hillary Clinton threatened her. In the past she has described this alleged threat in some detail

Soon after, Broaddrick says, she ran into Hillary Clinton at a political rally Broaddrick had promised friends she would attend. Hillary shook her hand and thanked her for everything she had done for Bill. To Broaddrick, the gesture felt like a threat to stay silent.

Same link as above (and by the way Jonathan Cohn and Ryan Grim's whole post is well worth reading (unlike this one))

That's it (as far as I know). Hillary Clinton is accused of shaking Juanita Broaddrick's hand and thanking her. Really. As far as I know her claim is the strongest evidence in favor of Trump's accusation. This is absolutely exactly nothing. It sure doesn't fit the standard definitions of "bullied", "attacked", "shamed" or "intimidated."

Other efforts to understand what the hell Donald Trump might have in mind (and what he wants us to believe) were made by Glenn Kessler and Michelle Ye Hee Lee working over time at the Washington post quote and check Trump

“Hillary Clinton attacked those same women, attacked them viciously.”

They don't seem to have any firm guess as to what specific claim he would make if pinned down (which he won't be). The phrase "those women" implies at least Broaddrick, Willey, and Jones. However, the only case they even consider is Lewinsky (who has never accused Bill Clinton of assaulting or harassing her).

One of the interviews that Clinton’s critics have pointed to is a Jan. 27, 1998 interview on the Today Show, saying it showed Clinton was discrediting allegations by then-White House intern Monica Lewinsky.


“I mean, look at the very people who are involved in this, they have popped up in other settings,” Clinton told Matt Lauer. “This is the great story here, for anybody willing to find it and write about it and explain it, is this vast right-wing conspiracy that has been conspiring against my husband since the day he announced for president.”


at the time of the interview, Lewinsky also denied there had been a relationship. Her lawyer had submitted an affidavit on Jan. 12 from her saying she “never had a sexual relationship with the president.”

so Hillary Clinton allegedly discredited Lewinsky by claiming (incorrectly) that Lewinsky had not committed perjury.

Note that the utterly absurd accusation that "Clinton was discrediting accusations by ... Monica Lewinsky" before Lewinsky made such allegations is still being discussed. It is completely 100% ridiculous, but it seems to be the best "Clinton's critics" can do (I definitely trust Glenn Kessler and Michelle Ye Hee Lee to be tough on Clintons).

They link to a full fact check by Michelle Ye Hee Lee here She gives the accusation that Hillary Clinton “savaged their dignity and shamed them,in an advertizement by a pro-Trump PAC three Pinocchios. The only evidence actually related to Hillary Clinton that the add presents is the interview which aired while Lewinsky was still denying having had sex with Bill Clinton. The accusation that by saying Lewinsky told the truth when under oath, Clinton "savaged" her "dignity" is utterly totally absurd.

The rest of the claims are about “The Clinton effort." Note the absense of a first name before the "Clinton." Here the claim is that Hillary Clinton is responsible not only for her husband's actions but also for the actions of his aids and advisors.

The accusations against Hillary Clinton are clearly unsupported by any evidence and utterly contemptible. The more important point is that they are frequently reported without any mention of their groundlessness, which is despicable journalism.

Thursday, October 06, 2016

Robert Frank on Frankness

Robert Frank is brilliant and extraordinarily able to both explain and critique the assumtion that the world is in Nash equilibrium.

He explains why game theory tells us " that rational observers should conclude that failure to disclose relevant information implies that the information must be as damaging as it could possibly be. " Yet Donald Trump won't reveal his tax returns.

Frank presents a plausible (indeed convincing) explanation for our failure to act a agents in Nash's model would.

First he discusses the standard case in which the signal is a guarantee made by a producer to purchasers of the product.

Theory fails in this scenario for the same reason it seems to have failed for Trump’s tax returns: Seeing is believing. It’s one thing to deduce from an abstract theory that undisclosed information is as unfavorable as it could possibly be. But it’s quite another thing to witness unfavorable information firsthand. Because our powers of attention and imagination are limited, knowing there must be a bombshell in Trump’s tax returns is actually significantly less damaging than seeing the bombshell itself. (Think of your visceral reaction when you heard about Trump’s nearly $1 billion loss, compared with the vaguely negative impression you had of his tax situation beforehand.)

Frank is so stimulating that he stimulated me to defend the empirical relevance of the concept of Nash equilibrium. I don't believe the following argument at all, but I think it holds together. It is also possible that the apparent non Nash equilibrium actions are based on the theorists misunderstanding of the game people are actually playing.

Uninterestingly, it is always possible to make up a utility function to justify any behavior. So if Trump would find it horribly painful to publish his tax returns and doesn't care much about becoming president, then he wouldn't publish them even if they looked beautiful. If voters know this about Trump, then it makes sense to not infer anything from his secrecy. This argument is silly -- it is always possible to reconcile anything with Nash equilibrium by assuming people really really want to do whatever they did.

But I think there is a less silly defence in this case. Consider a low information voter who doesn't know whether Trump has released his tax returns (they may be few in number but they exist). This voter draws no inference from the unknown fact that Trump has kept his returns secret. However, if he were to release them and reporters were to discuss the bombshells at great length, it might get through to the resolutely news ignoring low information voter. Now if everyone who is paying any attention assumes that Trump's returns are as bad as they could be (without him actually being prosecuted). It becomes rational to keep them secret to avoid coming to the fugitive attention of the lowest information voters. This is a general issue. In the simple games used to discuss the issue, it is assumed that information transmission is perfectly efficient, so consumers know what sellers have made public. That's not the way I consume. I don't check if some product has a warrenty or guarantee before buying it. I don't read the limited warrenty after I buy it. I might check (maybe) if the product turns out to be defective. Since I don't know which products come with guarantees, it isn't easier to sell me a product with a guarantee. However, I have, in my life, taken advantage of warrenties (once or twice). If all consumers were like me, it would be best for producers of the highest quality products to make no guarantees.

Since I don't bother to check, I don't know what I have and haven't been told. In the models, it is assumed that I know this automatically and that it requires no effort at all to deduce the implications.

Again, I think Frank's explanation is correct and that this story is silly.

Wednesday, October 05, 2016

Benchmarks, Models, and Hypotheses

I have been wondering about the frequent use and alarming rhetorical power of the word "benchmark". It often appears in the phrase "benchmark model," which is inconvenient, because I want to contrast benchmarks and models and don't want to write about the difference between benchmark models and other models.

Here I use "hypothesis" to refer to a collection of statements which we think might be true, such that we are eager to find out if they are all true, "model" for a collection of statements which we know are false but which might be a useful approximation to the truth, and benchmark for a model, which we wish to use only by contrasting it with models which we think might be useful approximations to the truth.

I imagine hopes followed by disappointments in the following order.

1) (compound complex) statement P might be true and P implies Q which we can observe.

2) Q is false so P isn't true, but P might still be a useful approximation to the truth because other implications of P are approximately true.

3) All the attempts to use P to approximate reality have failed, because each implication is far from the truth. P has been modified every time we try to use it, so the implication (which would be useful if correct but which is incorrect) is eliminated. We can fit and observed pattern after observing but continually fail to predict anything correctly. Work starting with P shares the fault of totally undisciplined empiricism which can describe but not forecast.

4) However, P is a useful benchmark. We can understand each of the stylized facts by remembering why each proves P false by noting how P had to be modified to fit the fact.

I think macroeconomics is reaching the 4th stage. The DSGE models which have dominated academic work for decades are based on assumptions which ( it is now asserted) were always assumed to be false. They are not especially useful for forecasting (and it is now asserted that they were never meant to be used to forecast). They offer limited guidance for policy in a crisis, because the crisis occurs exactly when one of the standard assumptions failed. However, they are still used as benchmarks. New models are presented as modifications of a standard model. One modification is made per article. Insights are obtained, because the modified assumption must cause the difference in results between the benchmark model and the new model.

My view is that the claim that a something is a useful benchmark might be false.

In fact, I think it is similar to the claim that a model is a useful approximation to reality. A model is a useful approximation if it gives approximately accurate conditional forecasts. It is used by calculating what the outcomes caused by different policies would be if the model were the truth. It is a useful approximately if the conditional predictions of outcomes conditional on policies are approximately accurate. The useful model is used to understand approximately how things would be different if different policies were implemented. Similarly a benchmark model is used to understand how things would be different if different assumptions were true. So we determine the effect of, say, some financial friction by comparing a new DSGE model with the financial friction to the standard DSGE model without it. Again the effort is to see how changing something changes outcomes. The difference might be that policy makers can't really eliminate the financial friction, so the actual outcome is compared to something which can be imagined but not achieved. However, the claims are roughly equally strong. Blanchard discusses considering a policy and considering a distortion as if they were the same sort of considering. "They can be useful upstream, before DSGE modeling, as a first cut to think about the effects of a particular distortion or a particular policy".

I think the choice of a benchmark is important because one modification is considered at a time. If implications were a linear function of assumptions, then it wouldn't matter from to which model one made a change. But, they aren't. The way in which an unrealistic DSGE model differs from the same model with a financial friction can be completely different from the way in which the real world would be different if a financial friction were eliminated.

But I think it there is a more important problem with accepting a DSGE model as at least a useful benchmark. The result has been that the vast majority of models in the literature share many of the implications of the benchmark model. So, for example, if the benchmark model has Ricardian equivalence, so do most of the modified models. The result is that if one surveys the literature and attempts to see what it seems to imply about the effects of the timing of lump sum taxes, it sure seems to imply there are probably no such effects. Most models imply no effect. The possibility of improving outcomes with temporary lump sum tax cuts is not discussed. When such cuts were proposed in the USA in 2009 (as part of the ARRA stimulus bill) many economists argued that policy makers were ignoring the results of decades of academic research. In fact, they were ignoring the implication of the standard benchmark model which was used, just as a benchmark, in spite of its poor performance.

This is the same pattern seen following the stronger hope that a model might be a useful approximation. The model is introduced with the expressed hope that it might be a useful approximation. Implications are derived. They turn out to be false. It is noted that models are false by definition, and that other implications of the model might be useful approximations. After years or decades, the model is no longer used by specialists in the field. However, it is still presented to outsiders as a useful first order approximation when it isn't. In this context "first order" means "according to the first model developed by my school of thought".

In both cases, actual practical implications are derived through a process which is completely invulnerable to evidence.

I am writing this, because the more diplomatic critics of mainstream academic macroeconomics insist that the models, which they find unsatisfactory, are useful benchmarks.

an example from a not so diplomatic critic . I think this claim is made without any consideration of the possibility that it might be false, and, indeed, a damaging falsehood. It is the least one can say if one isn't willing to tell people that they have wasted decades of their working life. But that doesn't mean that it isn't more than one should say.

A simple example illustrating the danger of changing one assumption at a time. The model is just the original Lucas supply function. The idea is that output is chosen by suppliers who don't observe the price level, so it is equal to the actual price level minus the rational forecast of the price level. This implies that output is a white noise and the location of the distribution of output doesn't depend on the behavior of the price level and therefore doesn't depend on monetary policy. With a standard assumption (or approximation) it implies that the expected value of output conditional on data available to agents is a constant which doesn't depend on monetary policy. This is the policy ineffectiveness proposition which lead Sargent and Wallace to note that, in their model, the optimal policy was to set the inflation rate to some desired target and ignore everything else. Notably this is the policy mandate of the European Central Bank. There are two counter arguments, neither of which amounts to much. The first, is that agents in the model are assumed to have rational expectations and so automatically know the policy rule. It is much more reasonable to assume that agents are boundedly rational and learn the policy rule. It was correctly argued that, given the other assumptions, this learning will have only temporary effects and that the rational expectations assumption will become true in the long run. It was later argued (based on massive evidence) that the current unemployment rate affects the future non accelerating inflation rate of unemployment, that is, that cyclical unemployment becomes structural, that is there ther is hysteresis. In this case, supply depends not only on price level prediction errors but also on the time varying natural rate. It was correctly argued that, in this model, the optimal policy was to target inflation -- the expected level of output didn't depend on policy. Here, in passing, it is worth noting that the additional assumptions mentioned above which were required to get from "location" to "expected value" become critical [Cite Pelloni et al].

But consider a newly installed monetary authority setting policy for an economy populated by boundedly rational agents who have to learn the policy rule. The authority should think what would happen she were less of an inflation hawk that people expect (not with rational expectations but with the actual beliefs of the boundedly rational agents in the economy). The result would be temporarily higher output while agents learn. This would cause permanently higher output because of hysteresis. Alone each of boundedly rational learning and hysteresis do not change the optimal policy. Together they change everything. The rule that only one change in the benchmark model is considered at a time can prevent people from seeing this. In fact, I think it has prevented most macroeconomists from seeing this.

OK Amateur partisan intellectual history after the jump.

A testable hypothesis always includes the core hypothesis of interest and auxiliary hypotheses required to obtain testable predictions (so Newton's model of the solar system includes the core hypotheses of his law of gravity and laws of motion and the auxiliary hypotheses that the sun and planets are rigid spheres and that the effects of all forces but gravity are negligeable). The problem is that the so called core hypotheses of the PIH, REH and EMH are not such thing. They are, in fact, always the same non-hypothesis that, ex poste one can find some utility fuction such that the actions of agents are consistent with rational maximization of the expected value of that utility functoin. This is true, because it must be true. It is agreed (and easily demonstrated) that the assumption that agents maximize something has no implications at all without some further assumptions about what they maximize. The core hypothesis is not falsifiable. If rejection due to failure of auxiliary hypotheses is not considered a reason to abandon the research program, then the research program is completely invulnerable to evidence.

This is a deadly problem, but I want to write about a different less important problem.

I am very irritated by the phrase "all models are false by definition". It mocks model testers who have demonstrated that some model has false implications. The implication is that the model testers misunderstood the aim of the model developers, incorrectly perceiving a model to be a hypothesis. Foolish salt water economists decided for some silly reason that the permanent income hypothesis, the rational expectations hypothesis and the efficient markets hypothesis were hypotheses. I claim that this shows bad faith. A statement is a hypothesis (with the associated scientific dignity) until it is proven false, then it turns out that it was always a model and the people who proved the statement false are silly.

The repeated use of the word "hypothesis" in the 50s 60s and 70s strongly suggests that the equations in question were not originally considered parts of models which were false by definition. Thomas Sargent's phrase "take a model seriously" sure seems to imply "treat a model as a null hypothesis." And, in fact Sargent once said (original pdf download here) that Lucas and Prescott were enthusiastic about hypothesis testing until he falsified too many of their hypotheses, and both independently said exactly that.

My recollection is that Bob Lucas and Ed Prescott were initially very enthusiastic about rational expetations econometrics. After all, it simply involved imposing on ourselves the same high standards we had criticized the Keynesians for failing to live up to. But after about five years of doing likelihood ratio tests on rational expectations models, I recall Bob Lucas and Ed Prescott both telling me that those tests were rejecting too many good models. The idea of calibration is to ignore some of the probabilistic implications of your model but to retain others.

Tuesday, September 27, 2016

Rudy is Appalling as is Politico

I am so naive that I can still be shocked by Rudolph Giuliani who said

"after being married to Bill Clinton for 20 years, if you didn’t know the moment Monica Lewinsky said that Bill Clinton violated her that she was telling the truth, then you’re too stupid to be president.”

The problem (revealing utter moral depravity) is that Monica Lewinsky never said that Bill Clinton violated her. She also didn't say he sexually harassed her. To Giuliani, there seems to be no difference between genuinely consensual sex by 2 adults and violation.

I am also so naive that I can still be appalled by "Politico's lack of editorial standards. Louis Nelson quoted Giuliani without noting that he conflated sex and violation. Giuliani's claim about what Lewinsky said is just false and an adequate reporter would have noted this fact.

Others note that Giuliani holds wives responsible for their husbands' infidelity. This is, in fact, part of a long now mostly obsolete Catholic tradition (which was never official doctrine) which includes the phrase "dovere congiugale" (which is Italian for women are obliged to have sex with their husbands even if they don't want to because that is the only way to prevent adultery).

But to me the key point is that, to him, it doesn't matter at all that Lewinsky took the initiative (not that there is anything wrong with that). This used to be the standard view here (in Rome) 2000 years ago (also later and moving to Istanbul in the law promulgated by Constantine which mandated the death penalty for voluntary premarital sex (obviously only if the father of the woman had high social class). I had hoped humanity had moved on.

As to the alleged stupidity, Giuliani knows a lot about how often spouses (such as his two wives) are the last to know.

I have heard of Clinton attacking Lewinsky a lot recently. I don't recall any such attacks. Now, one way or the other, it is not at all surprising that she was irritated with a woman who claims to have had sex with her husband (even if Lewinsky first said it to someone she thought was a friend in what she thought was strict confidence). Again, Rudy must know all about that. But when two people contest the facts, saying you trust and believe one isn't attacking the other.

I do think that what Clinton did was morally wrong especially given the gap in ages and huge gap in power. But "violated" is a strong word which, in context, means "raped". Giuliani doesn't understand the moral difference between voluntary sex and rape. Now I am not saying that I am therefore confident that he has raped. Based on his attitude, I strongly suspect that he has, but I know of no evidence of any specific rape (of course I know that Trump has been accused of rape by two women and of sexual assault by a third and I am very very sure that Donald Trump is a rapists (I note that here the standard for what I just typed to be both a tort and a crime is that it was false -- not knowing is no defense here).

Fact Check Fact Check

The AP got a facts wrong when fact checking Trump

TRUMP: "Had we taken the oil (in Iraq) -- and we should have taken the oil -- ISIS would not have been able to form."

THE FACTS: Donald Trump's assertion that the U.S. should have seized Iraq's natural resources would have required that it also seize control of the country and at no point was the U.S. in a position to do so.

To achieve Trump's stated goal of destroying Islamic State militants' revenue stream, the U.S. has bombed oil facilities in Iraq. The bombing was designed to render the oil facilities inoperable, but not destroy them, so Iraq could rebuild its economy with its oil when the conflict ended.

(Emphasis mine)

The AP is WRONG. The USAF has bombed oil facilities in Syria not in Iraq. This is actually very relevant. Trump claims the US could have cut off ISIS funding by seizing Iraqi oil. He displays his ignorance. ISIS is partly funded by selling Syrian oil (or was before the bombing). ISIS hasn't captured Iraqi oil fields.

They all look alike to Trump. Not just all Arabs but also all Arab countries. He has also incorrectly claimed that ISIS has captured and sold Libyan oil.

I guess it is hard to understand that proceeds from selling Syrian oil is (or was) a large part of the ISIS budget, because Syria has never been a major oil producer. It is possible, because the ISIS budget, while very large for a terrorist organization, is very small compared to the export revenues of a major oil producer.

Trump's inability to understand that Iraqi and Libyan oil fields are not the same as Syrian oil fields is one proof that he isn't qualified to be president. Failure to note that gross error is a gross fact checking error.

Watching (but not listening to) the Debate

I am not a sexist and I followed the brilliant advice the woman whose husband I am gave me in 2000. To understand how a presidential debate affects undecided voters, it is best to watch with the sound off. If you can't follow the words but only get visual impressions, then you might be able to understand the perspective of low info voters. In particular way back in the sad sad year 2000 she noted that Bush looked like a human being and Gore looked like a robot. That (and 5 supreme court justices) caused hundreds of thousands of deaths, a great recession and an indelible stain on the honor of the USA. OK maybe I am a sexist, but I can't stand to listen to Donald Trump for more than two minutes (I tried really I tried). He didn't look good. She looked calm and confident. But one thing that really struck me was the post debate. Trump was surrounded by his grim faced family. Then he ran off stage. Hillary and her husband shook hands and posed for photos, shared themselves with an adoring crowd, and acted like nice friendly people. I think this might make a difference.

Monday, September 26, 2016

Politico Fact Checking Clinton

I am very pleased that the New York Times, The Washington Post, The Los Angeles Times and Politico have decided to report the fact that Donald trump makes extraordinarily many false assertions. I'm fine with refraining from using the word "lie" which implies that the liar knows the truth. Given that he might be elected President, I hope he is lying. I fear he is delusional sincerely believing whatever it is convenient for him to believe or uninterested in the truth (to use the technical term that he is bullshitting). I also agree with Politico's decision to fact check Clinton too and to compare the two rates of false claims. But I disagree with the fact checking of Clinton. I rate Four of Politico's claims that Clinton erred to be False One as considering a difference of opinion a fact check One as refusing to interpret words with the usual meanings given the context of a political campaign One as interpreting normal political hyperbole as a claim of fact One actual false Clinton claim and one where it depends on what definition "has" has. So I say Politico is wrong three times as much as Clinton even though Kyle Cheney, Isaac Arnsdorf, Daniel Lippman and Daniel Strauss chose the most favorable 8 topics to debate Clinton and had the last word (actually the only words I read). The hyperbole one is ambiguous so maybe they are only 5/3 as error prone on the most favorable possible ground. In any case, I am quite sure that moving second, choosing the topics least favorable to Clinton and having the last word, Politico managed to beat Clinton 4 clear falsehoods to 1. Wow. Their claims 1. That Clinton falsely said she was very careful with classified information. First even if people who are very careful make mistakes (human perfection is impossible). Clinton must be compared with some other human being not an ideal. Politico makes no claim that anyone has ever been more careful. Clinton's alleged error was receiving an e-mail. This isn't an act. The error would be failing to denounce an aid who slipped up (after noticing the (C)s in documents. Obviously most US political journalists have lost their minds over Clinton's e-mails. I am confident that this will be another object lesson (used in journalism schools) of failed journalism like the Whitewater blood sports, the war on Gore, the run up to the Iraq war. Here I think Politico is treating the conventional wisdom as known fact and the prefered narrative as objective truth. In any case "very careful" is a matter of opinion and Clinton's claim is definitely not a false claim of fact. 2. Clinton said "I’ve met the standard that everyone running for president has met. ... healthy" I guess I have to go to hyperbole and standard political English for the every. Obviously Clinton isn't claiming that Lincoln reported his cholesterol levels. Aside from that, another fact checker seems to roughly rate Politico's claim as false with (according to Politico)
PolitiFact has found that Clinton’s health release in 2015 was on par with Mitt Romney’s and Barack Obama’s from 2012, and she’s released more details since her bout with pneumonia that led to a collapse outside a 9/11 memorial. Trump has left out more details than Clinton,
Note that this is in the fact check which claims her assertion is false. I claim Politico's assertion is false given the ordinary understanding of words (especially theirs). 3. 3. Trump’s “economic plans would ... include an estimated $4 billion tax cut for his own family just by eliminating the estate tax.” This is the one widely mocked on Twitter. Politico claims that Clinton's claim is false, because she treats Trump's claim that he has $10 billion as true. So one of Clinton's few alleged lies is only false because of a Trump lie. Also Politico is wrong again. The weasel word "estimated" makes the claim true. Clinton didn't mention that the estimate was provided by Donald Trump. This is not a falsehood. I rate Politico's claim to be false. 4. "So if you are a family living in an expensive city, you would be able to find an affordable place to call home.” Here Politico is right and Clinton is wrong. She claims a program which would help some families would make housing affordable to all who live in expensive cities. I think this may be an almost honest slip. She is trying to explain the purpose of the program. I can delete some words and a comma and make a two singulars plural to generate the very similar true claims Families living in expensive cities would be able to find an affordable place to call home. This is true. I think the "if you are" are a clumsy attempt to make an abstract benefit concrete by focusing on a hypothetical family. t is standard for politicians to falsely claim that programs will achieve their aims. But it is false. Current score Politico one out of 4. Sad. 5 “We’ve actually put in one place all of our plans,” she said while holding up a copy of her book “Stronger Together." “We have this old-fashioned idea if we’re asking you to support us, we should tell you what we’re going to do.” Politico notes that, if elected, Clinton won't do that because Congress will block her. It is absolutely standard for Presidential candidates to describe proposals as things that will be done. In any case, Politico's claim depends entirely on the referents of "we" and "us". If "we" are the Democrats who support the Clinton campaign (including almost all candidates for the House and Senate) and voters were support all of them, then the Democrats would have overwhelming majorities in the House and Senate and would pass Clintons proposals and then add more. In any case, Clinton's language is absolutely 100% standard. Politico is insisting that words not be interpreted as they are always always used in political campaigns. 6. Clinton said a technical true thing which sure sounds false “Your former guest, Donald Trump, has refused to actually admit that President Obama is an American, born in America.” This is true. Trump has frequently refused to admit that. He has also admitted it. I can change Clinton's true claim to a false claim adding one word “Your former guest, Donald Trump, has [consistently] refused to actually admit that President Obama is an American, born in America.” This claim is false, but Clinton didn't say that. Now I will add some more words which I really honestly often use to explain how "has" is used in English to Italians ( and how it does not translate the ha in the Italian passato prossimo) “Your former guest, Donald Trump, has, at least once in his life, refused to actually admit that President Obama is an American, born in America.” This is a clearly true claim. It is, I think the one and only correct clarification of Clinton's very brief and simple and therefore ambiguous statement. It is what she meant to say. Obviously she wasn't denying the existence of Trump's very famous recent admission. Here I think the Clinton's have a problem, because they are lawyers and know what exactly what some key words mean. I think the Politico writers sincerely thought they had caught Clinton in a slip of the tongue. But only because they don't understand the meaning of the word "has". I made the same error they did. I think that Clinton should have said "“Your former guest, Donald Trump, has frequently refused to actually admit that President Obama is an American, born in America.” This strengthens the claim but it also makes it clear that the claim that Trump has done something does not imply the claim that he has done only that. I rate Politico's claim as false (and admit again that I made the same error before re-reading the Clinton quote). Oh Christ they counted that one sentence as two false claims. That's crazy and she is right and they are wrong so I score Politico as 4 falsehoods to 1. 8 "“We have a Republican nominee for president who incites hatred and violence like we’ve never seen before.” This is clearly exaggerated. I'd say Osama Bin Laden beat Trump in the incitement business (so far). This is clearly normal hyperbole. I consider the truth value of Clinton's claim ambiguous. So one false claim and one normal exaggeration. Now I think they are very proud of themselves at Politico for drawing the unBallanced conclusion that Trump lies much more than Clinton. But I think they were very careful to leave no opening for critics to claim they had missed a Clinton falsehood. So their fact check of Clinton demonstrates their trouble with facts not hers.

Sunday, September 25, 2016

Macroeconomic Puzzles II Aggregate Supply

This is the second installment on general thoughts about Macroeconomics without a rational representative agent. The first installment is here. I'm going to continue to argue that it would be an improvement to go back to (some of) the macroeconomics of roughly 1970.

In the first installment, I claimed that Old Keynesian consumption functions which give consumption as a function of current and a few lags of personal disposable income and wealth outperform models based on intertemporal optimization and that investment (to the limited extent it can be modeled and forecast) is mostly fit by GDP growth with a significant effect of estimated real interest rates on residential investment. This means that I think closed economy models of aggregate demand from 1970 (really roughly from 1936) are much superior to later models.

Now I am going to go all the way and write that I think the best available model of aggregate supply is the 1960s era Phillips curve. First it is necessary to stress (again) that this was an expectations augmented Phillips curve. It differed even from more recently used a-theoretic Phillips curves, because anchored expectations were allowed.

To close the model it is necessary to have both a wage Phillips curve and a price inflation Phillips curve.

This is just exactly the model which was considered to be most thoroughly refuted in the 70s. The failure was the justification for the complete change in methodology. But I don't think it failed at all. The straw man of an expectations un-augmented Phillips curve was knocked down, but it hadn't been set up by old Keynesians in the 60s.

Notably, Paul Krugman is convinced that old Keynesian views on the Phillips curve have been vindicated writing "Tobin was right" also at length here. Blanchard recently wrote The US Phillips Curve: Back to the 60s which, I should stress asserts that the pattern of inflation and unemployment has become similar to that of the 60s and not that theory should return to 1960s theory (or 1960s absence of theory if you prefer).

The very old point as recorded in undergraduate macro textbooks (and for decades nowhere else) is that all macroeconmists really need from the supply side is a model of inflation. That combined with an empirical monetary policy rule (I guess just a Taylor rule) yields the one variable needed to estimate aggregate demand and output.

The fact is that extremely old fashioned Phillips curves actually worked rather well through the 1980s. They were abandoned because of oil shocks, theoretical arguments, straw man rhetorical tricks and fashion.

I think there are two necessary changes that were (and are) to be made. First the 1960s era Phillips curves went too far in correcting for expected inflation. It was assumed that there was nothing particularly special about 0% nominal wage inflation. In history it is very difficult to achieve actual reduction in nominal wages. It occurred in many countries during the Great Depression and in Greece recently, but even very high unemployment rates do not seem to be high enough to break through downward nominal wage rigidity. In the USA in the 60s this wasn't an issue so applied macroeconomists who focused on forecasting didn't discuss it much. Tobin in 1972 (and Solow in 1978) did.

Second, as argued by Solow and Samuelson in 1960, cyclical unemployment can become structural. This has been named hysteresis and it is clearly an extremely important issue here in Europe. In practice the first difference in unemployment matters much more for wage inflation than the level of unemployment.

The combination of anchored expectations and hysteresis means that economists got it backwards around 1980 -- fluctuations in unemployment lasted longer than fluctuations in inflation. The costs of policy makers' confidence that disinflation would be painful briefly but beneficial in the medium run were immense.

Anyway more thoughts here

Saturday, September 24, 2016

Macroeconomic Puzzles

Narayana Kocherlakota wrote a brilliant and brief post "On the Puzzling Prevalence of Puzzles".

I can't summarize Kocherlakota (just read it) but the key critique is as follows

To an outsider or newcomer, macroeconomics would seem like a field that is haunted by its lack of data, especially good clean experimental data. In the absence of that data, it would seem like we would be hard put to distinguish among a host of theories with distinct policy recommendations. So, to the novice, it would seem like macroeconomists should be plagued by underidentification or partial identification.

But, in fact, expert macroeconomists know that the field is actually plagued by failures to fit the data – that is, by overidentification.

Why is the novice so wrong?

The answer is the role of a priori restrictions in macroeconomic theory.


The mistake that the novice made is to think that the macroeconomist would rely on data alone to build up his/her theory or model. The expert knows how to build up theory from a priori restrictions that are accepted by a large number of scholars. (Indeed, in the academe, that’s exactly what it means to be an expert macroeconomist.) Those restrictions are what give the models their empirical content. As it turns out, the resulting models actually end up with too much content – hence, the seemingly never-ending parade of puzzles.

I think the prevalence of puzzles is no more puzzling than the fact that the squares in a crossword puzzle aren't filled in. The puzzles are the point of the exercize. In particular, researchers need problems which are neither to easy nor to hard. Easy problems have been solved decades, centuries or millennia ago. Hard problems won't be solved before tenure decisions are made. The macroeconomic puzzles are just difficult enough. Furthermore the huge gap between the standard DSGE model and reality means that the solution to one puzzle creates another puzzle.

JEC at Mean Squared Errors puts it much better than I could

Consider the macroeconomist. She constructs a rigorously micro-founded model, grounded purely in representative agents solving intertemporal dynamic optimization problems in a context of strict rational expectations. Then, in a dazzling display of mathematical sophistication, theoretical acuity, and showmanship (some things never change), she derives results and policy implications that are exactly what the IS-LM model has been telling us all along. Crowd -- such as it is -- goes wild.

And let's be clear: not even the most enthusiastic players of the macroeconomics game imagine that representative agents or rational expectations are, in any sense, empirical realities. They are conventions, "rules of the game." That is, they are arbitrary difficulties we impose on ourselves in order to demonstrate our superior cleverness in being able to escape them.

I add, however, that some assumptions are made, because it is too difficult to manage without them. We know that we don't have rational expectations, but we don't know how we actually do form expectations. The macroeconomist can't wait for psychologists (and sociologists) to finish their research program. Efforts to relax the rational expectations assumption have ended either with even less plausible mechanical assumptions or with extreme mathematical difficulty in models which are otherwise as simple as possible.

As usual, the challenge to the young macroeconomist goes back to Keynes. The General Theory of Employment Interest and Money begins with book 1 containing models which are not difficult enough (aside from the fact that they were explained clearly and in detail a year later by Hicks). It also includes Chapter 12 on long term expectations (beauty contests and all that) clearly presenting problems too hard for Keynes. Then thereare warnings really to not trust a Phillips curve (not called that 23 years before Phillips) and discussion of how wage setting is an extremely complicated and probably incomprehensible social process. So there are the parts which were finished at least 79 years ago and the parts which might maybe be finished 79 years from now (but I doubt it)

Here (as almost always) I am following Krugman

I’d divide Keynes readers into two types: Chapter 12ers and Book 1ers. Chapter 12 is, of course, the wonderful, brilliant chapter on long-term expectations, with its acute observations on investor psychology, its analogies to beauty contests, and more. Its essential message is that investment decisions must be made in the face of radical uncertainty to which there is no rational answer, and that the conventions men use to pretend that they know what they are doing are subject to occasional drastic revisions, giving rise to economic instability. What Chapter 12ers insist is that this is the real message of Keynes, that all those who have invoked the great man’s name on behalf of quasi-equilibrium models that push this insight into the background – from John Hicks to Paul Samuelson to Mike Woodford – have violated his true legacy.

The lack of puzzles is due to the fact that the puzzle addressed in book 1 is solved in book 1 and the problems posed in bok declare themselves to have "no rational answer". Neither provides a good dissertation topic. They do provide useful policy guidance. Keynes wrote that there will be manias, panics, and crashes no matter what policy makers do, and that they can deal with the aftermath by temporarily increasing government investment or consumption. If that's as good as macroeconomics can do then it's a very boring research program which reached it's apex the day it started. But it sure would be better than what ma macroeconomists did in 2008 with internal debates which weakened already limited influence on policy makers who did crazy things.

I am now going to write a long boring unoriginal post on which problems in macroeconomics are too easy and which are too hard. Aggregate demand is too simple. An IS curve works very well. Economists can create a problem by arguing that it shouldn't work and declaring its success to be a puzzle and others can let us have our fun. But they would be foolish to pay us for our play.

The accounting identity is that aggregate demand is equal to private consumption + private investment + government consumption + government investment + exports - imports. In standard DSGE models the last four terms are not microfounded. there is just a random variable for GDP minus private consumption minus private investment. I don't think it is wise to ignore foreign trade (especially not when trying to apply models to countries other than the USA). Here I think the problem is that exchange rates fluctuate wildly. Those fluctuations matter, but no one has found a rational explanation. So either one accepts irrationality or one leaves the effects as an undiscussed unexplained disturbance term. In particular and importantly, aggregate consumption is much much too simple. It can be fit using current disposable personal income and any crude measure of wealth (ordinary non-human wealth). It helps to add a few lags of current disposable personal income. This is rather important, because it has a huge effect on estimated multipliers and the lags are needed to fit the response to shifts in fiscal policy (that is get a multiplier of around 1.5 and not around 8). My view is that Keynes said ust about everything useful to be said about aggregate consumption with two exceptions. He didn't discuss circulating credit and living off of credit cards (because they didn't exist then) and he didn't recognize the important role of housing equity as one of the key forms of wealth which affects consumption.

I do seriously think that list of omissions is more or less adequate and complete. I argue this at great length here.

Now this is interesting, because Friedman's permanent income hypothesis has a central role in contemporary DSGE macroecomics. One of the two dynamic equations corresponding to the D in DSGE is the Euler equation, which has no place at all in Keynes. It also just so happens that the implications of the Euler equation are a leading source of puzzles and it is, by now, widely hated even by the open minded Simon Wren-Lewis who wants to give DSGE the benefit of every doubt and the very central (states) New Keynsian who works near a great lake Martin Eichenbaum. Keynes's argument was that future aggregate income is very hard to predict, so while the ratio expected future income to current must be considered when studying individual consumption, it is can and should be neglected by macroeconomists. I know of no evidence against this position.

Investment is much trickier. It is the topic of the dread chapter 12 (among others). It is, in fact, hard to fit and harder to forecast private investment. Here I think a large part of the problem for DSGE is the decision to model investment as a scaler and identify all of it with business fixed capital investment. Residential investment and inventory investment are not included in standard DSGE models. This is odd, because inventory investment is discussed constantly by practical forecasters who talk about the latest business cycle. Also it should be clear since 2008 that housing investment is extremely important.

I report some 1960s style econometrics of investment here. Here I learn (from Krugman) as usual that useful knowledge was abandoned in the current dark ages of macroeconomics

Back in the old days, when dinosaurs roamed the earth and students still learned Keynesian economics, we used to hear a lot about the monetary “transmission mechanism” — how the Fed actually got traction on the real economy. Both the phrase and the subject have gone out of fashion — but it’s still an important issue, and arguably now more than ever.

Now, what you learned back then was that the transmission mechanism worked largely through housing. Why? Because long-lived investments are very sensitive to interest rates, short-lived investments not so much. If a company is thinking about equipping its employees with smartphones that will be antiques in three years, the interest rate isn’t going to have much bearing on its decision; and a lot of business investment is like that, if not quite that extreme. But houses last a long time and don’t become obsolete (the same is true to some extent for business structures, but in a more limited form). So Fed policy, by moving interest rates, normally exerts its effect mainly through housing.

Here it is worth noting that while macroeconomists have worked very hard to include financial frictions in DSGE models, they still don't include a housing sector (as far as I know). This is very odd (have I missed a flourishing literature). I have some thoughts as to why housing might be ignored. First back to consumption. Housing wealth does not cause high consumption in a model with a rational representative consumer. The consumer's wealth in terms of consumption goods increases, but so does the price of the consumer's consumption bundle including housing services. Housing equity can relax liquidity constraints with HELOCs but the representative agent can't face a liquidity constraint. Housing equity can reduce precautionary spending as someone who, for example, is laid off can sell her house and live in a smaller house. But the whole economy can't sell its houses.

Notably the apparent effect of wealth on consumption (separately from its role as a predictor of future income) was rejected because it is hard to micro found

I would argue we built the first UK large scale structural econometric model which was New Keynesian but which also incorporated innovative features like an influence of (exogenous) financial conditions on intertemporal consumption decisions. [4]


Our efforts impressed the academics on the ESRC board that allocated funds, and we won another 4 years funding, and both projects were subsequently rated outstanding by academic assessors. But the writing was on the wall for this kind of modelling in the UK, because it did not fit the ‘it has to be DSGE’ edict from the US. A third round of funding, which wanted to add more influences from the financial sector into the model using ideas based on work by Stiglitz and Greenwald, was rejected because our approach was ‘old fashioned’ i.e not DSGE. (The irony given events some 20 years later is immense, and helped inform this paper.)


[4] Consumption was of the Blanchard Yaari type, which allowed feedback from wealth to consumption. It was not all microfounded and therefore internally consistent, but it did attempt to track individual data series.

I havent read the linked paper. I can see a problem with using stock market indices as wealth which directly affects consumption. They should summarize future dividends which are future income and so already considered in the permanent income hypothesis. Here the problem is that stock fluctuations are very large compared to the tiny fluctuations in the achieved present value of future dividends. If there is noise in stock prices, one might ask if it helps explain consumption and how it deviates from the consumption of hypothetical rational representative agent. There is and it does, but facing that fact requires one to abandon the rational expectations assumption and join one side of a furious debate in finance. Now I think it is important to understand why contemporary models of monetary policy and its effects totally suppress the fact about what sort of investment is affected which Krugman was taught back in the age of the dinosaurs. I suppose it is probably really because it was considered a harmless simplification and it is very important to have few variables if the benchmark of one's benchmark model is a VAR. But I can see a number of reasons why housing is problematic. The first is that there was a huge housing bubble which is very hard to reconcile with the rational expectations assumption. It is much easier to explain a huge increase in stock prices as the effect of an increase in expected future technological progress. Second it is hard to understand how monetary policy affects housing investment. First it is necessary for the monetary authority to affect real interest rates (and that already loses the hard core new Classicals). Then it is necessary that fluctuations in short term interest rates cause fluctuations in mortgage interest rates. I think the high correlation doesn't make sense (so long term bonds and mortgages are good buys when short term interest rates are high). The 30 year fixed interest rate mortgage is a very extreme case of nominal rigidity. Their existence makes no sense. I think that, like foreign exchange markets, housing demand is incomprehensible and must be treated as an unexplained and unpredictable source of shocks. On the other hand, there are useful simple things to say about investment. First it is well fit by a flexible accelerator which gives high investment to GDP when GDO growth is high and low investment when short term nominal interest rates minus lagged inflation is high. In particular, the vulgar estimate of a real interest rate helps explain housing investment (and not so much if at all business investment). The problems are too hard (chapter 12 and business fixed capital investment, housing bubbles and housing investment) or solved long ago. Now the old IS model has stong implications which are very different from those of standard DSGE models. In the old model, there was no Ricardian equivalence. I think there is no evidence of Ricardian effects at all. I think the IS curve works find and the only problems are that it is very old and that no optimization under constraint is considered when writing it. Aggregate supply (coming fairly soon -- lags are important). Part II here