Competition among parties and power: an empirical analysis

According to commonsense wisdom, under proportionality a small centrist party enjoys an excess of power with reference to its share of seats (or votes) due to the possibility of blackmailing the larger ones. This hypothesis has been challenged on a theoretical ground, with some empirical support. In this paper we use simulation to test its validity. Our results strongly provide evidence that the hypothesis is actually wrong. What occurs is a transfer of power from the periphery of the political spectrum towards the center, but the major gainers are the large centrist parties and not the small ones.