In the American Association for Public Opinion Research study, the researchers found surveys, as they did in 2016, understated care for Republicans and for former President Donald Trump.
Josh Clinton, a Vanderbilt University professor and AAPOR task force member, explained that "there was a systematic error that was found in terms of the overstatement for Democratic support across the board.
"It didn’t matter what type of poll you were doing, whether you’re interviewing by phone or internet or whatever. And it didn’t matter what type of race, whether Trump was on the ballot or was not on the ballot" he told the news outlet.
The AAPOR website was down for maintenance Monday.
Polls were better at foretelling support for Joe Biden against Trump in the presidential election than for Democrats in state elections, the study revealed — a contest Biden won by over 7 million ballots. In general, backing for Biden in the surveys was 1 percentage point higher than his actual vote, the Post reported.
In 2020, polling pointed to Democrat gains in the House; rather, Republicans came nearer to closing the majority gap.
According to the Post, the study discovered "that the polls overstated Biden’s support more in whiter, more rural, and less densely populated states is suggestive (but not conclusive) that the polling error resulted from too few Trump supporters responding to polls. A larger polling error was found in states with more Trump supporters.
"It’s possible that if President Trump is no longer on the ticket or if it’s a midterm election where we know that the electorate differs in the presidential election, that the issue will kind of self-resolve itself," the task force member said.
"But if the polls do well in 2022, then we don’t know if the issue is solved or whether it’s just a phenomenon that’s unique to presidential elections, with particular candidates who are making appeals about ‘Don’t trust the news, don’t trust the polls’ that kind of results in taking polls becoming a political act."
The AAPOR task force went through 2,858 polls, including 529 national presidential race polls and 1,572 state-level presidential polls. They discovered that the surveys overstated the margin between President Biden and former President Donald Trump by 3.9 points in the national popular vote and 4.3 percentage points in state polls, the Post reported.
Polls minimized Trump care in almost every state and by an average of 3.3 percentage points overall. Polls in Senate and gubernatorial races suffered from the same difficulty.
Polling in senatorial and gubernatorial races revealed a similar pattern, overstating the margin for Democrat candidates versus their Republican opponents, the Post reported. When state-level presidential surveys were removed from the sample, the error level was even higher, the news outlet reported.