Strategic voting and constituency context: Modelling party preference and vote in multiparty elections

We examine the role of strategic motivations in mediating the relationship between underlying political preferences and vote choice, in a multiparty, single member, simple plurality system, and examine the role of constituency context in determining the scope for strategic voting. Political preference data from the British Election Panel Survey, 1997–2001, were modelled with mixed multinomial logit models. Latent variables were used to model the stable party political traits underlying observed preferences, allowing correlation between choices and so avoiding the restrictive assumption of independence from irrelevant alternatives. Ranked approval ratings were used to characterize the underlying political preferences in the presence of insincere voting. From these models we estimate that approximately 9% of votes cast may have been affected by strategic factors. In keeping with ‘Duvergers law’, the smallest of the three main parties, the Liberal Democrats, were found to be most affected by strategic voting.