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Thursday, September 09, 2004

I told Rasmussen so

The latest Rasmussen tracking poll released Wednesday Sept 8 (based on Sunday Monday and Tuesday) shows Bush up by 1.7 % Bush 48.2 - Kerry 46.5. This is close to the result reported Monday, which was Bush up by 1.1%. This comes as a surprise to the Rasmussen reports, but not such a big surprise to me.

Monday Rasmussen wrote ""Our current poll (showing the President ahead by just over a point) includes a Saturday sample that is way out of synch with all the days before it and with the Sunday data that followed. In fact, Saturday's one-day sample showed a big day for Kerry while all the days surrounding it showed a decent lead for the President.It seems likely that Saturday reflects a rogue sample (especially since it was over a holiday weekend). But, it remains in our 3-day rolling average for one more day (Tuesday's report). If we drop the Saturday sample from our data, Bush is currently ahead by about 4 percentage points in the Rasmussen Reports Tracking Poll. "

I wrote

"Assuming Rasmussen doesn't doubt that the Saturday poll really was conducted according to standard Rasmussen methodology, it is not a good idea to drop it. The proposed procedure appears to be to average three daily polls unless one day's results is significantly different from the results on the other two days. Given the fact that sampling error is almost exactly normally distributed, this procedure would give a worse distribution of estimates (mean preserving spread) than the standard procedure of averaging over three days even if one day stands [out]"

On Monday Rasmussen said the best guess of Wednesday's report would be bush up by about 4%. I said the best guess would be 1.1 %. 1.7% is closer to 1.1% than 4%. Of course this is mostly luck, and I wouldn't change my mind if the Bush lead had been 4% or more, but I did tell him so.

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