PROPORTIONALITY, DISPROPORTIONALITY AND ELECTORAL SYSTEMS

Different PR methods should be seen not as being more proportional or less proportional than each other but as embodying different ideas as to what maximizing proportionality means and, by extension, what minimizing disproportionality means. Each of the main methods of PR (d'Hondt, Sainte-Laguë, largest remainders) generates its own index of proportionality and, thus, its own way of measuring disproportionality. Applying these indices to competitive elections of the period 1979-1989 shows a high correlation between the rankings produced by the various methods, but the ordering of countries is sufficiently different to require a choice to be made between the indices. © 1991.