Confronting 2016 and 2020 Polling Limitations. Pew Research Center. Courtney Kennedy et al. April 8, 2021
The 2016 and 2020 elections raised questions about the state of public opinion polling. Some of the criticism was premature or overheated, considering that polling ultimately got key contours of the 2020 election correct (e.g., the Electoral College and national popular vote winner; Democrats taking control of the Senate). But the consistency with which most poll results differed from those election outcomes is undeniable. Looking at final estimates of the outcome of the 2020 U.S. presidential race, 93% of national polls overstated the Democratic candidate’s support among voters, while nearly as many (88%) did so in 2016.
This report summarizes new research into the data quality of Pew Research Center’s U.S. polling. It builds on prior studies that have benchmarked the Center’s data against authoritative estimates for nonelectoral topics like smoking rates, employment rates or health care coverage. As context, the Center conducts surveys using its online panel, the American Trends Panel (ATP). The ATP is recruited offline via random national sampling of residential addresses. Each survey is statistically adjusted to match national estimates for political party identification and registered voter status in addition to demographics and other benchmarks. The analysis in this report probes whether the ATP is in any way underrepresenting Republicans, either by recruiting too few into the panel or by losing Republicans at a higher rate. [Note: contains copyrighted material].
[PDF format, 25 pages].