Something's rotten in the state of Denmark

Wednesday, November 17, 2004

More debunking of Exit Polls

Here, courtesy of Herr Kaus, is a Mayflower Hill blog post including an interview with exit pollster Warren Mitofsky, where Mitofsky himself shrugs off the suggestions that exit poll disparities point towards irregularities.

One thing he confirmed to me is that the average deviation to Kerry in the completed version of the exit poll was +1.9%. This figure was arrived at by comparing and averaging, on a precinct to precinct level, the exit poll data and the precinct vote returns. When asked if the full 1.9% deviation could be explained by non-response bias (Kerry voters being more likely to complete the exit poll than Bush voters), he said, "It's my opinion, but I can't prove it." He went on to say that it would be an impossible thing to "prove" categorically because there exist an infinite number of variables that could have a micro-impact on the exit poll which could combine for a statistically significant impact. These factors ranged from the weather to the distance from the polling place some of his poll takers were forced to stand. He is also trying to determine whether there is a statistically significant correlation between certain types of precincts and the non-response deviation. Again, right now he feels the most reasonable and logical explanation of the average 1.9% deviation for Kerry was non-response bias.

One possibility he was able to rule out, though, is touch screen voting machines that don't leave any paper trail being used to defraud the election. To prove this, he broke down precincts based on the type of voting machine that was used and compared the voting returns from those precincts with his own exit polls. None of the precincts with touch screen computers that don't leave paper trails, or any other type of machine for that matter, had vote returns that deviated from his exit poll numbers once the average 1.9% non-response bias was taken into account.

...The data that was reported on election day had not been "weighted" for turnout yet. Once an accurate projection of overall voter turnout is made, the raw data that the exit pollsters collect is plugged into a complicated methodological system that I won't begin to pretend to understand. The point is, though, that a sort of "correction" is made to the raw numbers that everyone saw on Wonkette and other sites. The bloggers who ran those numbers either didn't know about the system of "weighting" the exit polling data, or didn't bother to point it out.

As Mickey points out, this is the exit pollsters method of saving their asses: hey, them numbers weren't corrected yet! Serves you bloggers right for posting them before we cooked 'em up with all the dressings.