Pre-electoral coalitions in comparative perspective: A test of existing hypotheses

Despite the vast coalition literature, pre-electoral coalitions have never been at the center of any systematic, cross-national research. Given their prevalence and potential impact on government composition and policies, this represents a serious omission in our knowledge of coalitions. I begin to remedy this situation by testing two hypotheses found in the literature on party coalitions. The first is that pre-electoral coalitions are more likely to form in disproportional systems if there are a sufficiently large number of parties. The second is that pre-electoral coalitions are more likely to form if voters face high uncertainty about the identity of future governments. These hypotheses are tested using a new dataset comprising legislative elections in 22 advanced industrialized countries between 1946 and 1998. The results of the statistical analysis support the first hypothesis, but not the second.