Philip Bump: “To what extent, if any, are polls missing Trump’s support? Clearly, some state polls missed the mark in 2016, leading forecasts to assume he had less of a chance of winning than he did. Was it because Trump supporters weren’t included or were wary of talking to pollsters? Research after the fact assessed the idea that pollsters were being misled.”
“‘[T]he notion that Trump supporters were unwilling to express their support to pollsters was overblown, given the scant evidence to support it,’ a report from the Pew Research Center stated. ‘A committee of polling experts evaluated five different tests of the `shy Trump` theory and turned up little to no evidence for each one. Later, a researcher from Yale and Pew Research Center conducted separate tests that also found little to no evidence in support of the claim.’ But we can evaluate this idea another way. A number of recent polls at the state level have measured both the presidential election and Senate races. If people were wary of revealing support for Trump specifically, it’s safe to assume that Trump would trail the Republican Senate candidates. For the most part, though, the opposite is true.”