This article investigates the impact of political and electoral institutions on party system stability in 40 democracies, including Brazil. Party stability is analyzed using the Electoral Party Variation (EPV) indicator, based on the Effective Number of Electoral Parties (ENEP). The political and electoral institutions of interest include electoral magnitude, electoral formula, and an approach derived from Sartori (strong, feeble, and moderate electoral systems). The analysis employs four models using the generalized estimating equation (GEE) method for panel data (40 cases, […]