Improving election prediction internationally

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Science  03 Feb 2017:
Vol. 355, Issue 6324, pp. 515-520
DOI: 10.1126/science.aal2887

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Using global data for election predictions

Assumptions underlying election result predictions have been questioned recently. Kennedy et al. assessed more than 650 executive office elections in over 85 countries and performed two live forecasting experiments. They analyzed a variety of potential predictors theorized to be of importance, ranging from economic performance to polling data. Elections were about 80 to 90% predictable, despite uncertainties with available data. Polling data were very important to successful prediction, although it was necessary to correct for systematic biases. Unexpectedly, economic indicators were only weakly predictive. As data sources improve and grow, predictive power is expected to increase.

Science, this issue p. 515


This study reports the results of a multiyear program to predict direct executive elections in a variety of countries from globally pooled data. We developed prediction models by means of an election data set covering 86 countries and more than 500 elections, and a separate data set with extensive polling data from 146 election rounds. We also participated in two live forecasting experiments. Our models correctly predicted 80 to 90% of elections in out-of-sample tests. The results suggest that global elections can be successfully modeled and that they are likely to become more predictable as more information becomes available in future elections. The results provide strong evidence for the impact of political institutions and incumbent advantage. They also provide evidence to support contentions about the importance of international linkage and aid. Direct evidence for economic indicators as predictors of election outcomes is relatively weak. The results suggest that, with some adjustments, global polling is a robust predictor of election outcomes, even in developing states. Implications of these findings after the latest U.S. presidential election are discussed.

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