Party Systems, Democratic Positions, and Regime Changes: Introducing the Party-System Democracy Index

One of the most important global political developments is the current wave of autocratization. Most research identifies this as an executive-led process, while others highlight the role opposition actors play in resisting it. We combine this work into a common framework asking, how (anti-)democratic are party systems? Party-system literature emphasises and measures policy differences, while we conceptualise party systems’ democratic positions highlighting to what extent divergent regime preferences are prevalent across parties. To estimate this dimension, we introduce the Party-System Democracy Index (PSDI), capable of tracking regime preferences across party systems from 1970 to 2019 across 178 countries and 3,151 country-years. We implement well-established content, convergent, and construct validity tests to confirm the PSDI’s reliability. Finally, we also show that the PSDI is an important predictor for regime changes in either direction and that changes in the PSDI can signal a looming regime change. This work provides a new framework for studying regime changes and contributes to the renewal of the party-systems literature.