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Non-Compulsory Voting in Australia?: what surveys can (and can't) tell us Jackman, Simon Uploaded 08-25-1997 Keywords turnout Australian politics compulsory voting political participation counter-factuals surveys non-response measurement error social-desirability heuristic question-order effects simulation parametric bootstrap Abstract Compulsory voting has come under close scrutiny in recent Australian political debate, and influential voices within the (conservative) Coalition government have called for its repeal. Conventional wisdom holds that a repeal of compulsory voting would result in a sizeable electoral boost for the Coalition; the proportion of Coalition voters who would not vote is thought to be smaller than the corresponding proportion of Labor voters. But estimates of Coalition gains under a return to voluntary turnout are quite rough-and-ready, relying on methods hampered by critical shortcomings. In this paper I focus on assessing the counter-factual of non-compulsory turnout via surveys: while turnout is compulsory in Australia, responding to surveys isn't, and the problems raised by high rates of non-response are especially pernicious in attempting to assess the counter-factual of voluntary turnout. Among survey respondents, social-desirability and question-order effects also encourage over-reports of the likelihood of voluntarily turning out. Taking non-response and measurement error into consideration, I conclude that survey-based estimates (a) significantly emph{under-estimate} the extent to which turnout would emph{decline} under a voluntary turnout regime; but (b) emph{over-estimate} the extent to which a fall in turnout would work to the advantage of the Coalition parties. Nonetheless, the larger of the Coalition parties --- the Liberal Party --- unambiguously increases its vote share under a wide range of assumptions about who does and doesn't voluntarily turnout.

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A Compositional-Hierarchical Model of Abstention under Compulsory Voting (poster) Katz, Gabriel Uploaded 06-18-2008 Keywords compulsory voting abstention compositional data hierarchical modelling MCMC. Abstract Invalid voting and electoral absenteeism are two important sources of abstention in compulsory voting systems. Previous studies in this area have not considered the correlation between both variables and ignored the compositional nature of the data, potentially leading to unfeasible results and discarding helpful information from an inferential standpoint. In order to overcome these problems, this paper develops a statistical model that accounts for the compositional and hierarchical structure of the data and addresses robustness concerns raised by the use of small samples that are typical in the literature. The model is applied to analyze invalid voting and electoral absenteeism in Brazilian legislative elections between 1945 and 2006 via MCMC simulations. The results show considerable differences in the determinants of both forms of non-voting; while invalid voting was strongly positively related both to political protest and to the existence of important informational barriers to voting, the influence of these variables on absenteeism is less evident. Comparisons based on posterior simulations indicate that the model developed in this paper fits the dataset better than several alternative modeling approaches and leads to different substantive conclusions regarding the effect of different predictors on the both sources of abstention.