Challenger Quality as a Moderator of the Incumbency Advantage in Personalized PR Systems: Applying the RDD to Irish Local Elections

This paper addresses the question of how the quality of list competitors affects the personal incumbency advantage in PR systems. For this purpose we adopt the Regression Discontinuity Design for the case of Irish Local Elections between 1942 and 2014 in which the Single-Transferable-Vote (STV) electoral system is used. We exploit the special characteristic of local elections in Ireland until 1999 in which members of the national parliament were allowed to hold dual mandates, i.e. they were allowed to be represented in local and national parliaments simultaneously. Since national parliamentarians are well-known we can expect that these candidates are well recognized by voters and thus lower the incumbency advantage of marginally elected local legislators. In general, our findings demonstrate evidence of a clear incumbency advantage for local candidates. This effect is moderated, however, by the decision of national parliamentarians to compete in a local election. In these cases, we find no evidence of a local incumbency advantage. This finding is robust to various different modeling strategies and further corroborated by the fact that the local incumbency advantage became strong after the elections of 1999 in which the dual mandate was abolished.