Sunday, December 04, 2016

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.

and

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.

[skip]

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.

2 comments:

LosGatosCA said...

I am not a professional economist but it seems to me that macroeconomics is just microeconomics scaled up is just plain wrong.

If microeconomics was flawless (LOL) I guess you could make some sort of argument for that concept, but I think the limitations of that assumption are self-evident.

derrida derider said...

"[the idea] that macroeconomics is just microeconomics scaled up is just plain wrong."

Of course - and that is pretty much the very first thing taught in any introductory macroeconomics course. It is why macroeconomics is so different in method and approach from microeconomics, and why most macroeconomists would reject Noah's suggestion that the field adopt microeconomic methods.

And it is also the reason why progress in macroeconomics is so slow and characterised by repeated dead ends. There is no easy answer; nature can sometimes be very unkind to would-be scientists. Put another way, macroeconomists appear dumb only because the questions they are asked to answer are so hard.

I just wish they were correspondingly humble.