Too Much Information: The Mixed Performance of Seat Betting Markets At The Federal Election

Advance Summary

1. Seat betting markets, considered by some to be highly predictive, returned an indifferent final result at the 2013 federal election, overpredicting the number of Labor losses by at least seven and predicting fourteen seats incorrectly.

2. Better results were achieved not only by local/state projections based on polling data but also could have been achieved by a simple reading of the national polls.

3. Seat betting markets in the final week most likely misread the election because of an overload of contradictory data.  They placed too much emphasis on local-level polling and internal polling rumours and too little on national polling.

4. Prior to the final week of the campaign, however, seat betting markets performed well in projecting an uncertain situation that was difficult to model.

5. Seat betting markets were most accurate immediately following the return of Kevin Rudd.  However this probably reflects on the modelling skills of bookmakers rather than punters.

6. Modellers wanting to know what seat totals betting markets expect should look at direct seat total markets rather than attempting to derive that information via complex and uncertain processes from seat betting markets.

7. Final direct seat total markets were very accurate.

2013 Federal Election Late Counting: Tasmania Senate

Tasmania Senate: Current Assessment
2 Labor, 2 Liberal, 1 Green certain
Final seat between PUP, Liberal, Sex Party
Current assessment: All three parties have realistic chances.  There is no clear favourite, but PUP are in my view narrowly the best placed. 

The AEC currently expects to declare the result (subject to challenges) at 2 pm Thursday.  The button is expected to be pressed on Wednesday 10 am. 


Final Result Thread: Final result and analysis will be posted on the new thread here.


NB A report published on Tasmanian Times (18 Sep) claiming the Sex Party has won was a bad case of premature ejaculation.  Counting has not finished, the button has not been pressed yet and the ABC Calculator is not an exact model of what happens when it does. TT has since acknowledged the unclarities in the situation.

Summary: 

I have added this summary (which will be edited as needed) because this article is getting very long and very complex.  What follows below is my full analysis of the current Tasmanian Senate late count, some of which is highly technical in nature.  The current situation is that three different parties - first Palmer United, then the Liberals, then the Sex Party, have been shown as leading on the ABC Senate Calculator at various points.  However the calculator assumes all votes are above-the-line ticket votes, and in practice preferences flow slightly more weakly than the model expects, especially if a party has lots of below-the-line votes.