OPEN LEFT Tue Jul 29, 2008
A Gallup / USA Today poll came out yesterday showing John McCain ahead among likely voters, 49%-45%. The article on the poll is kind of funny, since it spends most of its time explaining why Gallup came out with another poll, taken during the exact same time, showing Obama ahead 48%-40%, and also why the likely voter sample in the poll is so different from the registered voter sample, which still shows Obama ahead 47%-44%. I have some more quick thoughts on this poll:
The poll should be considered the equivalent and opposite outliers to the four polls showing Obama ahead by double digits: Research 2000, Zogby and, last month, LA Times / Bloomberg and Newsweek.
......
Outliers are an inevitable aspect of polling. One in twenty polls will be off by more than the margin of error, which in the case of most national polls is plus or minus three or four points for each person in the poll. That is, one in twenty polls will be off by at least seven points, and one in forty polls will favor McCain by at least seven points. Given that McCain had led in two of the last eighty polls according to Pollster.com, there is nothing surprising in the least about these results. An outlier in favor of McCain once every forty polls is an inevitable side effect of the most heavily polled election of all time. It would actually have been more surprising if there were no outliers in favor of McCain, ever.
Seems to me Gallup is an outlier among other polls showing the race is quite even in terms of the popular vote?