Pre-print, Working paper: In several cantons in Switzerland the regional government, i.e. a set of governors who share the executive power in the canton, is elected according to an original voting rule, in which voters can vote for several candidates (up to a maximal number of votes). Up to some details, these elections are instances of what is known in Social Choice Theory as “Committee Approval Voting”. The paper makes use of data from a panel survey collected during the 2011 Zurich cantonal election to check whether a strategic voting theory is consistent with individual behaviour observed during that election. We show that roughly 70% of the individual decisions on candidates are consistent with our model of rational voting.