Report into 2019 polling failure

Yesterday, the Association of Market and Social Research Organisations, the national peak industry body for research, data and insights organisations in Australia, released its report into the polling failure for the 2019 Australian Federal Election. 

Unfortunately, the Australian pollsters did not share their raw data with the AMSRO inquiry. So the inquiry was constrained. Nonetheless, it found:

The performance of the national polls in 2019 met the independent criteria of a ‘polling failure’ not just a ‘polling miss’. The polls: (1) significantly — statistically — erred in their estimate of the vote; (2) erred in the same direction and at a similar level; and (3) the source of error was in the polls themselves rather than a result of a last-minute shift among voters.

The Inquiry Panel could not rule out the possibility that the uncommon convergence of the polls in 2019 was due to herding. 

Our conclusion is that the most likely reason why the polls underestimated the first preference vote for the LNP and overestimated it for Labor was because the samples were unrepresentative and inadequately adjusted. The polls were likely to have been skewed towards the more politically engaged and better educated voters with this bias not corrected. As a result, the polls over-represented Labor voters.

While the report was hampered by the limited cooperation from polling companies, it is well worth reading.