Political space representations with approval data

Data from political elections provide a snapshot of the political landscape of a country or region. This snapshot is filtered, and maybe also distorted, through the lens of the voting method in place. The standard Plurality Voting method, by virtue of asking every voter to report only the maximum of his or her preferences, might provide too little data for an accurate snapshot. We analyze data from two large-scale field experiments in Germany, where voters employed Approval Voting for both parties and candidates. The analysis reveals that the underlying political landscapes, as perceived by the voters, are inherently multidimensional and cannot be reduced to a single left-right dimension, or even to a two-dimensional space. We compare the obtained representations with those derived from party positions as revealed by the 'Wahl-o-Mat' voting advice application, and further compare the results with those of the W-NOMINATE procedure.