In the 2016 US presidential election, both national and state polls gave the impression that election night would bring clear Democratic gains, but that was not the case.

Pollsters have indeed underestimated Donald Trump’s support critically cradle states that year. However, the national polling averages were quite accurate compared to the popular vote, which Hillary Clinton won. However, the 2020 national polls had an even larger margin of error.

The American Association for Public Opinion Research, a trade group of the polling industry, said that public opinion polls ahead of the 2020 presidential election were the most inaccurate in the last 40 years.

“The problem is substantially a matter of reaching respondents who are reluctant to participate in surveys,” said Charles Franklin, a professor of law and public policy at Marquette University who conducted the 2012 Marquette Law School survey.

Pollsters believe they have largely identified the reasons behind polling errors in 2016. According to a report from a panel of experts published in Public Opinion Quarterly, a key factor was monitoring voter education levels.

Polling expert Charles Franklin explained in an interview with Euronews that Trump supporters display a unique distrust of politics, the media and polling organizations, a factor that may have contributed to inaccuracies in 2016 and 2020.

To further address the issue of underrepresented Trump supporters, some pollsters are now weighting their data based on the results of the 2020 election, with the goal of better reflecting the views of voters who may be less inclined to respond to polls.

“Surveyors have adopted new methods of reaching samples using email and text in addition to traditional phone calls,” Franklin explained.

These expanded methods of contact are complemented by modified sampling procedures designed to reach respondents who had previously shown reluctance to participate, particularly in areas with strong support for Trump in the past.

Many pollsters have adjusted their methodologies, largely due to inaccuracies seen in the 2020 election.

“We will know after the election if these efforts have worked,” Franklin said.