This study directly compares survey data on social attitudes collected from an opt-in sample of Voter Advice Application (VAA) users and a randomly recruited, probability-based online panel of respondents. While much research to date has focused on the demographic representativeness of VAA data, less is known about the attitudinal and other representativeness of that data. This study of Australian samples contributes to the emerging literature.

VAAs are proliferating as a source of ‘big data’ among public opinion and political science researchers, despite concerns over the representativeness of the opt-in samples. During July 2016, VAA developer Election Compass collected email address details for approximately Australian 40,000 users of its application in the weeks prior to the 2016 Australian federal election. In November 2016, this study surveyed the sample of VAA users on their attitudes towards a range of Australian social issues.  In December 2016, the same questionnaire was administered to a probability-based sample, using an identical mode of administration and similar response maximisation techniques. The questionnaire contains a broad range of questions designed to identify dimensions of socio-political attitudes in Australian society. Comparing the composition of dimensions and relationships between variables within the data contributes to our understanding of incidental samples such as VAA users, and the extent to which we can and should make inferences from VAA-generated data.