Nate Silver & Co. is out with the ratings….
American election polls are about as accurate as they’ve always been. That doesn’t mean polls will always identify the right winner, especially in close elections. (As a simple rule of thumb, we’ve found polls “call” the right winner 80 percent of the time, meaning they fail to do so the other 20 percent of the time — although upsets are more likely to occur in some circumstances than others.) But the rate of upsets hasn’t changed much over time.
Before we go any further, I want to direct you to the latest version of FiveThirtyEight’s pollster ratings, which we’ve updated for the first time since May 2018. They include all polls in the three weeks leading up to every U.S. House, U.S. Senate and gubernatorial general election since then,1including special elections, plus a handful of polls from past years that were missing from previous versions of our database. You can find much more detail on the pollster ratings here, including all the polls used in the ratings calculation. Our presidential approval ratings, generic congressional ballotand impeachment trackers have also been updated to reflect these new ratings, although they make little difference to the topline numbers…
|POLLSTER||METHODOLOGY||NO. OF POLLS||AVG. ERROR||BIAS||ADV. PLUS-MINUS|
|ABC News/Washington Post||Live||5||1.7||R+0.9||-4.1|
|Mason-Dixon Polling & Research Inc.||Live||7||2.8||R+1.0||-3.0|
|Mitchell Research & Communications||IVR/Online||6||2.5||R+0.9||-2.0|
|Siena College/New York Times Upshot||Live||47||3.6||R+1.3||-1.7|
One more key reminder now that the Iowa caucuses are only three months away: Some types of elections are associated with considerably larger polling errors than others. In particular, presidential primaries feature polling that is often volatile at best, and downright inaccurate at worst. Overall, presidential primary polls in our database mispredict the final margin between the top two candidates by an average of 8.7 points. And the error was even worse, 10.1 points, in the 2016 primary cycle. Leads of 10 points, 15 points or sometimes more are not necessarily safe in the primaries…
Rasmussen is third form the BOTTOM.….