Seat Betting As Bad As Anything Else At Predicting The 2019 Federal Election

Advance Summary

1. Seat betting markets, sometimes believed to be highly predictive, did not escape the general failure of poll and betting based predictions at the 2019 federal election.

2. Indeed, seat betting markets were significantly worse predictors of the result than the national polls through the election leadup, and only converged with polling-based models to reach a prediction that was as inaccurate as the national polls at the end.

3. Seat betting predicted fourteen seats incorrectly, but all of its errors in Labor vs Coalition contests, in common with most other predictive methods, were in the same direction.

4. Seat betting markets did vary from a national poll-based outlook in several seats, but their forecasts in such cases were about as often misses as hits.

5. This is the third federal election in a row at which seat betting has failed to show that it is a useful predictor of classic (Labor vs Coalition) seat-by-seat results in comparison with simpler methods.  

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With all House of Representatives seats now declared, it's time for a regular post-election feature on this site, a review of how seat-by-seat betting fared as a predictive method.  I have been interested in this subject over the years mainly to see whether seat betting contained any superior insight that might be useful in predicting elections.  In 2013 the answer was a resounding no, in 2016 it was a resounding meh, and surely if seat betting could show that it knew something that other sources of information didn't, 2019 would be the year! Even if seat betting wasn't a very good predictor, if it was not as bad as polling or headline betting this year, that would be something in its favour.

2019 saw the first failure in the headline betting markets since 1993, but it was a much bigger failure than that.  In 1993 Labor were at least given some sort of realistic chance by the bookies, and ended up somewhere in the $2-$3 range (I don't have the exact numbers).  This year the Coalition were $7.00 to Labor's $1.10 half an hour before polls closed - just an implied 14% chance -  and Sportsbet had already besmirched itself in more ways than one by paying out early (which I think should be banned when it comes to election betting, but that's another story).  The view that "the money never lies" has been remarkably immune to evidence over the years, but surely this will be the end of it for a while.

Poll Roundup And Seat Betting Watch: The Polls Are Getting Closer (To Each Other)

2PP Aggregate 51.8 to Labor (2016 preferences) (-0.1 since last week)
51.4 to Labor (with One Nation preference adjustment)
Current seat projection assuming polls are accurate c. 80 Labor 65 Coalition 6 crossbench (+/- lots!)
Polls appear to be "herded" which can increase risk of error

Time for another instalment of the week in polling and seat betting, delayed slightly by an interstate trip.  As of last week the United Australia Party were going through a bit of a purple patch, polling 5% in Newspoll and above their 2013 result in a bunch of seat polls.  This hasn't lasted; all their poll results this week have been in the 3-4% range, and in three WA YouGov-Galaxy seat polls they did worse than their 2013 results (in one case much worse; the other two only very slightly.)

This week's action in the minor party primaries came from the Greens who polled 14% in Ipsos, 11 in Morgan, 12 in Essential and 9 in Newspoll.  Ipsos (especially) and Morgan have form for exaggerating the Green vote and Essential's reading of the Green vote lately has been quite volatile, but even so the party doesn't seem to be in too bad shape, with the issues mix at this election helping it (that is an understatement.) That said, the Greens have finally struck the candidate problems that have hitherto affected everybody else.