For those of you who follow columns like this one about polls, one of the challenges is comparing the results of one poll versus another. There are many variables, including the methods and track records of each pollsters; whether they are surveying likely voters, registered voters or all adults; or, the percentages they determine for sample size of each demographic group, among other things.
Jumping in to help is Nate Silver of the respected FiveThirytEight.com
blog, which has just reached a deal to be hosted
this year by the New York Times. Silver, a master of mathematical analysis, first put those skills to use
analyzing baseball statistics and developing a model to predict the future performance of players and teams. Later, he decided he could use his modeling to analyze polls and election data the same way.
Silver has come out with his ranking of pollsters when it comes to their accuracy of forecasting election results. The key statistic Silver uses is "Pollster-Introduced Error" which he says "reflects the amount of error that a pollster introduces above and beyond that which is unavoidable due to things like sampling variance."
Here's the top 15 from his list
in order of which pollsters had the lowest PIE. It include firms that did a minimum of 10 polls during the period he analyzed. The ratings are based on polling for President, Senate, House and gubernatorial races since 1998:
1. Field Poll (primarily California)
2. ABC News/Washington Post
5. University of Cincinnati's Ohio Poll
6. Selzer & Co.
7. NBC News/Wall Street Journal
9. Mason-Dixon Research
10. Pew Research
12. Market Shares
13. Public Policy Polling
14. Blum & Weprin
15. Rasmussen Reports
Four polls which Poll Watch frequently cites came in 17th through 20th in this order: Fairleigh Dickinson University, Rutgers University, Marist Institute and Siena College. CBS News/New York Times was 24th, Franklin & Marshall College was 29th, the Los Angeles Times was 34th, Quinnipiac University was 45th and Fox News/Opinion Dynamics was 46th.
Near the bottom of the list was Research 2000, American Research Group, InsiderAdvantage and Zogby Interactive.
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