Electoral systems and unimagined consequences: Partisan effects of districted proportional representation

Electoral systems scholarship has frequently focused on the role of distric t magnitude-the number of seats awarded per district-in shaping party syste ms, The basic insight is that an increase in district magnitude will tend t o increase the number of parties and party system fragmentation. District m agnitude varies in many electoral systems, but cross-national research summ arizes this distribution with a single number. We argue here that magnitude variation itself has important partisan political consequences, which we r efer to collectively as the "variance effect," The variance effect creates disadvantages for urban political interests relative to rural interests, ma king it more difficult for urban and other correlated interests to convert support Into parliamentary representation and to obtain unfragmented parlia mentary representation. We demonstrate, with analyses of twenty-four electi ons in sixteen countries, that the variance effect operates as theoreticall y predicted and is surprisingly important.