Dynamic effects of electoral laws

A change in electoral laws is expected to substantially alter political outcomes as voters and elites adjust their behavior to new rules. However, testing the causal implications of this theory using electoral reforms has been difficult because election results before a reform are not the appropriate counterfactual for election results after a reform. This article leverages electoral reform in New Zealand and Norway and the synthetic control method to approximate the appropriate counterfactuals: election results in the period after reform, had the reform not occurred. In both the countries, I find evidence that electoral reform had a short-term effect on the size of the electoral party system, but no evidence of a lasting effect on the electoral party system.