When Donald Trump won the presidency in 2016, it revealed a flaw in the polling system. In the lead up to the election, Hillary Clinton had a 7-point edge, leading many to predict that she would win. However, as exit-poll data on November 8 began to roll in, the pre-election poll data was found to be faulty.
According to a report by the New York Post, one of the issues with the pre-election data, which lead many to underestimate then-presidential candidate Trump’s chances of winning, involved running on an assumption.
A group of 18 states had voted for the Democrat during every election since 1992 – six consecutive presidential elections – leading many polling organization’s to assume those states would continue to do so during the 2016 election.
“In 2016, a lot of us assumed we knew what would happen in Michigan and Wisconsin,” said Anthony Salvanto, the head pollster for CBS News.
As a result, many polling groups didn’t reach out to many voters in those states. It wasn’t until election day that they realized the value of contacting everyone.
“It was a great lesson for us pollsters,” Salvanto stated. “Even if you think you know what will happen, poll it if you can.”
As this year’s midterm elections draw closer, Salvanto isn’t relying on the same data he had used in years prior. Instead, he is putting more stock in the ongoing tracking poll conducted by CBS and less on telephone polling, which relies on a random sample.
A tracking poll selects a panel that consists of thousands of votes. CBS checks in with them regularly over the course of a set number of months. This allows them to evaluate shifts in public attitudes more effectively.
Only two major surveys had predicted Trump’s victory in 2016, and both were tracking polls.
For the 2018 midterms, CBS has a panel of 5,700 registered voters, the vast majority of which live in the 50 to 60 districts that may switch from Republican to Democrat or vice versa.
Based on the polls, Salvanto’s data indicates that few House seats will actually flip, suggesting that the anticipated “blue wave” might not be coming. Instead, Salvanto predicts that 85 percent of House districts will likely stick with their current party affiliation.
However, a few swing districts could lead to a shift in the political makeup of the House, where Republicans currently hold a 43-seat majority.
“Right now, I think this election looks like a toss-up,” Salvanto stated. “We see a Democrat pickup in the House of Representatives in the 20-odd seat range, but Republicans could certainly hold on to the House.”
“Even though Republicans have not fared well in special elections so far this cycle, it does look like they will be turning out for the midterms,” Salvanto added. “So far we do not see a large number of Republicans saying they will flip and vote for a Democrat.”