%0 Journal Article
%T 2016 Presidential Statewide Polling¡ªA Substandard Performance: A Proposal and Application for Evaluating Preelection Poll Accuracy
%A Spencer Kimball
%J American Behavioral Scientist
%@ 1552-3381
%D 2019
%R 10.1177/0002764217735622
%X This study implements a statistical accuracy (SA) measurement for assessing preelection poll accuracy by comparing Mosteller (1949) Method 5 (absolute difference between poll results and election results) with the poll¡¯s margin of error (MOE) or credibility interval. The expectation is that 95% of poll results would be SA by falling between the poll¡¯s margin of error or credibility interval and the actual margin of victory. The new measurement is described and then applied to the statewide preelection polls from the 2012 Presidential (n = 331) and 2016 Presidential (n = 539) races using n = 182 polling organizations in the last 21 days of each election cycle. This analysis finds statewide preelection polling in 2012 had a 94% SA and was not statistically different from the expected 95%, while the statewide polling in 2016 had a 77% SA and a binomial test found the distribution differs significantly from the expected 95%. There is a significant difference in SA between the two election cycles, ¦Ö2(1, N = 870) = 45.24, p < .000. The 2012 biased polls favored the Republican candidate 68% of the time; however, a binomial test found this distribution did not differ significantly from the expected 50/50 distribution, .50, p = .167 (two-tailed), suggesting this was caused by random error. In 2016, biased polls favored the Democratic candidate 90% of the time, a binomial test indicated that the proportion was higher than the expected .50, p < .000 (two-tailed), suggesting a systemic bias
%K Polling
%K 2016 election
%K Trump
%K Clinton
%K Statistical Accuracy
%K Presidential Polling
%U https://journals.sagepub.com/doi/full/10.1177/0002764217735622