In this study, we argue that the perceived polarization of Americans along party lines is partially an artifact of the low response rates that characterize contemporary surveys. People who agree to participate in opinion surveys are more informed, involved, and opinionated about the political process and therefore hold stronger, more meaningful, and partisan political attitudes. This motivational discrepancy generates a bias in survey research that may amplify evidence of party polarization in the mass public. We test the association between response rates and measures of polarization using individual-level data from Pew surveys from 2004 to 2014 and American National Election Studies from 1984 to 2012. Our empirical evidence demonstrates a significant decline in unit response that is associated with an increase in the percentage of politically active, partisan, and polarized individuals in these surveys. This produces evidence of dissensus that, on some issues, may be stronger than exists in reality.
That is from a forthcoming piece by Cavari and Freedman in The Journal of Politics. For the pointer I thank an anonymous correspondent.