March 30, 2021 — The FiveThirtyEight statistical organization released their latest political pollsters’ accuracy ranking chart toward the end of last week — a study that included 592 survey research firms.
Grades from A+ to C/D were assigned to the firms based upon four criteria:
- Their 2020 election cycle precision
- The predictive category that suggests how successful the firm will be in the future
- The number of polls analyzed in this most recent cyccle, and
- hat the FiveThirtyEight team terms as the company’s “mean-reverted bias” factor.
Four polling entities earned the top A+ rating. They are:
- the Iowa-based Selzer & Company
- ABC News/Washington Post
- Siena College/New York Times
Another six received A ratings:
- Survey USA
- Landmark Communications
- Research & Polling
- Monmouth University
- Marist College
- Fox News
Seven more posted A- rankings:
- The Trafalgar Group
- Public Opinion Strategies
- CBS News/New York Times
- Mason-Dixon Polling & Strategy
- Public Policy Polling
- Emerson College
- Quinnipiac University
On the other end of the spectrum, 18 firms were at the bottom of the list but a dozen from this group conducted less than 10 surveys. Of those featuring more than 10 polls, the lowest ranked of the group were Nielsen Brothers Polling, the Humphrey Institute, FM3 Research, Opinion Research Associates, McLaughlin & Associates, and Brown University.
Selzer & Company has long been recognized as one of the country’s better pollsters based upon its strong record predicting the Iowa Caucus presidential results and other races most often from the Hawkeye State.
In 2020, 12 of 19 published polls projected Iowa Democrat Theresa Greenfield as leading Sen. Joni Ernst (R). Approaching Election Day, only two pollsters posted the incumbent ahead four or more percentage points: Selzer & Company and Insider Advantage. Sen. Ernst’s final victory margin was 6.6 percentage points. The IA firm came closest to the end result (Ernst, plus-6; actual, 6.6 percent). Surveying for the Des Moines Register newspaper, Selzer & Company again landed within the accuracy realm (Ernst plus-4).
The ratings also included the polling firms’ partisan bias factor. The bias swing in favor of one party or the other ranged from 4.7 points toward the Democrats (Survey Monkey) to a 3.1 sway for Republicans (MRG Research). The overwhelming majority of pollsters with the highest bias rating favored the Democrats. Of the 28 firms that registered a 2.0 or greater partisan bias factor, 26 favored Democratic candidates.