Does the Adoption of Inclusive Selectorates Influence Party Membership?

The Literature on party politics has identified two distinct phenomena: democratization in leadership and candidate selection methods (Pilet and Cross, 2014; Cross and Blais, 2012; Kenig, 2009; Kittilson and Scarrow, 2003; Bille 2001; Hazan and Rahat, 2010) and a decrease in the number of party members (van Biezen, Mair, and Poguntke, 2012; Scarrow and Gezgor, 2010). However, there is evidence that within the broad picture of membership decline, there are patterns of seasonal growth. These may be explained by the adoption of inclusive selection methods that give members a voice in determining who the party leader and legislative candidate/s will be. So-called 'instant membership' had been recognized in Canada and Israel, two of the nations which had early and long experience with inclusive methods (party primaries). This instant membership entails a rapid growth in the number of party members prior to primary contests, followed by a sharp decline when the contest is over, as members do not bother to stay.  In this paper we try to investigate whether similar trends in party membership can be traced in other nations that have adopted inclusive leadership selectorates. In other words, we ask whether, and in what manner, a change in the rules of games has affected the number of party members, by creating incentives for enrolling as (short-term) members. For this end, we use two large datasets that were recently made available: MAPP's party members' dataset (van Haute and Gauja, 2015) which provides merged data of membership figures in over than thirty nations, and leadership selection dataset (Pilet and Cross, 2014) which provides data on thirteen nations.