The power of an elector in the Spanish parliament: A study compared with power indices

Abstract

The main goal of this article is to study, from a game theory perspective, the composition of the Spanish Parliament according to Article 68 of the Spanish Constitution, although the proposed model is applicable to the reduction of other representation chambers. It even allows for the sporadic design of the chamber in periods of crisis such as those we are currently experiencing. We use power indices to analyse feasible allocations of seats among the circumscriptions, modifying the size of the Parliament and considering different minimum initial numbers of seats per province. We propose two modifications of the composition following the cubic root rule of the de jure population. Finally, we compare the results of the general elections of December 2015 and June 2016 for the election of the members of the Congress of Deputies (Spanish Parliament) with the current system, which distributes a total number of 350 deputies among the provinces, with an initial minimum of two deputies (system 350/2), with another distribution system that distributed 360 deputies with an initial minimum of one deputy per province (system 360/1).