Compulsory voting has come under close scrutiny in recent Australian political debate. Conventional wisdom maintains that a repeal of compulsory voting would result in a sizeable electoral boost for the conservative Coalition parties; the proportion of Coalition voters who would not voluntarily turn out is thought to be smaller than the corresponding proportion of Labor Party voters. But these estimates rely on methods hampered by critical shortcomings, and so the conventional wisdom is easily challenged or dismissed. I examine the use of surveys in assessing the counter-factual of non-compulsory voting, focusing on the 1996 Australian Election Study. While turnout is compulsory in Australia, responding to surveys isn’t; people who respond to surveys generally have more interest in politics than non-respondents, so it is unsurprising that survey respondents report a voluntary turnout rate approaching 90%. Respondents also tend to exaggerate the probability that they would voluntarily turn out. I draw on examples where the effects of survey non-response and over-reporting on estimates of turnout have been estimated (including the NES vote validation studies). Using these examples as a guide, I find that surveys overestimate the voluntary turnout rates likely to be encountered in Australia (55% to 70%, versus the survey estimate of 88.8%), and the extent to which a fall in turnout would work to the advantage of the Coalition parties. The Liberal Party still appears to benefit from a shift to voluntary turnout, though these gains are not as large as the conventional wisdom suggests.