Yes, Prime Minister: The key to forecasting British elections

We use our “PM and Pendulum” Model to forecast the outcome of the 2010 General election. The vote function of the model, aside from a cyclical dynamic, relies on approval of the prime minister as the sole predictor. We find that PM Approval predicts the vote (and vote intention between elections) more accurately than does Government Approval. Turning to the forecasting of seats, we examine the accuracy of the autoregressive model of the vote-seat translation against the uniform-swing model, which is widely used by pollsters and the media. Testing the alternatives on election data since 1910, our autoregressive vote-seat translation model proves superior to the uniform-swing model.