The Impact of Sample Size and Response Bias on Survey Results

Polls missed the 2016 election outcome and did even worse in 2020 on the margin, underestimating Donald Trump again. Should we believe the polls this time? What have pollsters changed? Have they overcorrected? In an era of one percent response rates for phone surveys and opt-in Internet panels, should we even talk about them in the same way? Michael Bailey finds that our theories about random sampling don’t really apply anymore. And weighting with larger samples does not solve our non-response biases. Brian Schaffner finds that weighting on several factors has increased, likely helping pollsters avoid undercounting Trump supporters. They both say survey research is important to get right but that the solutions are not obvious.