Replication Data for: Introducing the One-Party Membership Dataset: A dataset on party membership in autocracies

Recent literature on autocracies focuses on elite politics to study ruling party stability. I focus on the lowest level of the ruling party structure, party members, to introduce new data on party-based autocracies. Party members are unique connectors between ruling party and society, and ruling parties can recur to them for policy enforcement, political control, co-optation and legitimation to secure power. I present the One-Party Membership Dataset (OPAMED), a comprehensive dataset on party membership in autocracies, covering 42 ruling parties across party-based regimes from 1945 to 2020, and introduce two new variables: party size; and party membership volatility. The first variable measures the membership-to-population ratio, while the second measures the rate of co-optation growth from one year to the other. In conclusion, the OPAMED provides a new, flexible and easy-to-use toolkit on ruling parties in party-based autocracies.