Party novelty and congruence: A new approach to measuring party change and volatility

We propose a new three-dimensional approach to party newness and an interval index of party congruence/novelty. Building on this, we also propose a split-vote-by-congruence (SBC) approach to electoral volatility that employs the index. Four elections from different countries that exhibited different forms of party change are used to illustrate the approach. The congruence/novelty index corresponds to our qualitative case knowledge, and the SBC...