Election Predictions: An Empirical Assessment

Examination of 155 poll forecasts in 68 national elections since 1949 shows that errors average nearly twice what statistical theory would indicate. Polls predict the division of vote between major parties better than individual party percentages, leading to 85 percent success in picking the winner. The worst failures occurred in a few elections where most polls went wrong. Liberal party votes are correctly forecast, conservatives slightly underestimated. Improved polling methods have not led to better forecasts.