Strategic voting and effective representation thresholds: Evidence from three Spanish general elections

The extent of strategic voting in the Spanish general elections of 2000, 2004 and 2008 is estimated using a new measure of strategic incentives suitable for proportional representation systems that avoids some of the problems associated with lagged variables. Strategic behaviour increased from 12 to 33 per cent of the electoral base of the United Left Party, the major victim of strategic defection. This estimate is a conservative one as elite mobilisation is controlled for in the constituencies, which is unusual in the literature on strategic voting that uses regression‐based methods.