Before the emergence of polls in the 1930s, judgments from political insiders and experienced observers were commonly used for forecasting (Kernell, 2000), as they still are today. When making predictions, expert analysts are assumed to be independent, and they each have experience in reading and interpreting polls, assessing their significance during campaigns, and estimating the effects of recent or expected events on their results. Each expert can be expected to use a different approach and rely on at least somewhat different data sources when generating forecasts. Thus, combining experts’ judgments should increase forecast accuracy.
Use of expert judgment in the PollyVote
Since 2004, Polly periodically contacts a panel of experts to obtain their estimates of the incumbent’s share of the two-party popular vote on Election Day. Data on surveys from 2004 to 2016 are available in Graefe (2019).
Date N of experts Biden Trump April 16-20 12 52.3 47.7 May 15-18 12 52.2 47.8 June 18-22 13 53.8 46.2 July 21-24 12 55.0 45.0 August 18-22 11 53.2 46.8
- Graefe, A. (2019). Predicting elections: Experts, polls, and fundamentals. Judgment and Decision Making, 13(4), 334-344.
- Kernell, S. (2000). Life before polls: Ohio politicians predict the 1828 presidential vote. PS: Political Science and Politics, 33(3), 569–574.