Measuring party nationalisation: A new Gini-based indicator that corrects for the number of units

The study of the territorial distribution of votes in elections has become an important field of the political party research in recent years. Quantitative studies on the homogeneity of votes and turnout employ different indicators of territorial variance, but despite important progresses in measurement, many of them are sensitive to size and number of political parties or electoral districts. This article proposes a new ‘standardised party nationalisation score’, which is based on the Gini coefficient of inequalities in distribution. Different from previous indicators, the standardised party nationalisation score weights for the sizes of territorial units (such as electoral districts) within a country, and considers the different numbers of territorial units in different countries.