Extra- and within-system electoral volatility

We analyze the remarkable differences in the electoral success of new parties and compare the determinants of electoral volatility attributable to new versus established parties. We base our findings on an original data set of total volatility, extra-system volatility, and within-system volatility for 67 democratic countries across all regions of the world since 1945. The article makes three contributions. First, we show that it is important to distinguish between electoral volatility that represents vote shifts among established parties (within-system volatility) and shifts to new parties (extra-system volatility). Second, we provide descriptive information about total, within-system, and extra-system volatility for 67 countries. Third, we analyze the determinants of volatility. Our results show that the causes of within- and extra-system volatility differ markedly. In contrast to Powell and Tucker, for our broader range of countries and longer time period, there are several statistically robust positive findings.