Assessing swings in multi-party systems: The Indian experience

India has a single member, first-past-the-post system. Owing to the importance of wasted votes in a multi-party system, the relation between votes and seats cannot be explained by traditional swing analysis. In this paper a measure of vote-splitting 1 is developed and used to decompose changes in margins into the ‘swing’ and the ‘split’. This method of analysis is applied to the study of electoral change in India and its usefulness for prediction is examined.