Germany Going Postal? Comparing Postal and Election Day Voters in the 2017 German Federal Election

The proportion of voters casting their votes by mail days or even weeks before election day has risen from initially five per cent to nearly thirty per cent in the 2017 German federal election. At the same time, the differences in election results between postal and election day voters are increasing, reaching a record at the Bundestag election in 2017. Against this background, it seems particularly surprising that there are only a small number of empirical studies on postal voting in Germany. For an evaluation (of the development) of postal voting, it is crucial to investigate the factors responsible for the different election results between the two voter groups. This requires more precise knowledge of postal voters and how they differ from voters who cast their ballots on election day. Using data from the German Longitudinal Election Study (GLES), we investigate in how far composition effects - differences between the voter types in the composition of factors potentially relevant for party choice - and association effects - differences regarding their vote functions or criteria applied for vote choice - can help to explain the different electoral outcomes. We conclude that the voter types do not differ substantially from each other with regards to their decision criteria but that their composition differs with regards to certain characteristics relevant for party choice.