Presidential Candidate Selection Process in Mexico: A New Index to Measure Internal Democracy in Political Parties

The process of candidate selection is one of the most important issues of the political parties' internal democracy. We propose an Internal Democracy Index (IDI) building on three basic dimensions: competitiveness, decentralization and inclusiveness to measure the levels of democracy of these processes. The IDI is applied to nine processes of presidential candidate selection in the three principal Mexican political parties -Partido Accion Nacional (PAN), Partido Revolucionario Institucional (PRI) and Partido de la Revolucion Democratica (PRD)-between 1999 and 2012. We show that PAN evidences highest levels of internal democracy, as compared to PRI and PRD, in particular, considering the levels of competitiveness. We argue that the IDI is useful to capture and compare the levels of internal democracy both synchronically and diachronically.