Luca Gamberi (King’s College London, UK)

Title: Maximal modularity and the optimal size of parliaments: how big should your parliament be?

An important question in representative democracies is how to determine the optimal parliament size of a given country. According to an old conjecture, known as the cubic root law, there is a fairly universal power-law relation, with a 1/3 exponent, between the size of an elected parliament and the country’s population. Empirical data in modern European countries support such universality but are consistent with a larger exponent. In this seminar, I will introduce the audience to this intriguing regularity and discuss the current state of social science research on the topic. I will then move on to introducing our model, which is derived from fundamental complex network theory. We will see how modelling the population of a democratic country as a random network, drawn from a “clustered” growth model, enable us to determine an optimal number of constituencies – and thus of representatives – for a given population. In particular, I will briefly show how the modularity of the population can be calculated analytically and that its functional relation with the number of constituencies is strongly non-monotonic, exhibiting a maximum that depends on the population size. following a criterion of maximal modularity allows we are able to predict that the number of representatives and show that it naturally scales as a power-law in the size of the population – a finding that is qualitatively confirmed by the empirical analysis of real-world data. 

Link to the seminar here

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