Our approach is broadly to predict the next election based on current opinion polls and the track record of polls in previous electoral cycles, allowing for change in opinion in the run up to the election.

The method allows for three main historical tendencies:

1. Governments being more likely to recover and oppositions fall back.
2. Parties moving back towards their long-run average level of support and/or the level of support at the previous election.
3. By far the least important tendency is for the Conservatives to over perform and Labour to under perform their vote intention figures in the polls when it comes to election day.

All three suggest a Conservative recovery and a Labour set back from autumn 2013.

The statistical regression methodology generates estimates of uncertainty and so prediction intervals (range of likely outcomes) and probabilities for key events are also provided with each forecast.

The forecast represents a way to think about the implications of current opinion polls for the outcome of the next general election in light of the historical relationship between polls and election results. It is the product of a statistical analysis of the data and not our personal opinion about what will happen.

Acknowledgements: See here.