Center for the Study of Democracy

Most federal second chambers give subunits equal representation. A few apply per capita representation, like most first chambers. Only Germany and Canada compromise between territorial and per capita representation. Both broadly allocate seats following S_i=SP_i ⁿ/∑P_k ⁿ, the only simple format without internal inconsistencies. Two values have been proposed for n. The rigid n=0.5 approximates the Canadian pattern but does not fit the German system. The flexible n=[1/logT-1/logS]/[1/logT-1/logP] takes into account the number of subunits (T) and total seats (S), for given total population (P). The flexible model better predicts seat allocation both in Canada and Germany. This model has been shown to apply to the European Parliament and the EU Council. Hence it may express what countries intuitively grope for when trying to strike a compromise between representations per capita and per subunit. As such, it does not fit the seat allocation of administrative subunits in unitary states, France and Italy.