The failures of seat polling have been a common subject on this site this year. See Is Seat Polling Utterly Useless?, Why Is Seat Polling So Inaccurate and How Did The Super Saturday Seat Polls Go?
The recent Wentworth by-election was difficult to poll because of a late strategic-voting swing of probably a few to several points from Labor to the winner Kerryn Phelps. All seven polls that polled a Liberal vs Phelps two-candidate preferred vote did actually get the right winner. But that is all the good news that there is. In so many other respects, the seat polls for the historic Wentworth by-election, perhaps the most polled seat in Australian history, were way wrong. And like other recent seat poll failures in such seats as Bass, Macarthur, Dobell, Lindsay and Longman, the failures were characterised not just by the polls being very wrong, but also by them tending to be wrong in the same direction. The problems go beyond small sample size, and beyond even the tendency of seat polls to be less accurate than their sample sizes say they should be. They point to systematic errors not random ones, and in this case, I suspect, to the oversampling of the politically engaged.
Showing posts with label Voter Choice. Show all posts
Showing posts with label Voter Choice. Show all posts
Friday, November 16, 2018
Friday, September 14, 2018
Wentworth By-Election: Prospects And Polls
WENTWORTH (Lib vs ALP, 17.8%)
Cause of vacancy: Resignation of Malcolm Turnbull
A by-election for Wentworth has been set down for Saturday 20 October following the resignation from parliament of the former Prime Minister, Malcolm Turnbull. This post will give an assessment of how this by-election stands in history and will also comment critically on polling. As I start it on 14 Sep I won't be brave enough to predict the winner yet, but I may do so later [edit: as of the final week I am not liking the Liberals' chances of holding off Phelps at all]. This post will be updated with new polls and changed assessments through to polling day.
By-elections often produce big swings against governments, but surely 17.8% is safe? After all, there has only been one larger swing in federal by-election history (20.1% in Wakefield, 1938). In fact there are at least two reasons not to take the seat's safety for granted. These are the historic circumstances of the by-election and the prospect of losing the seat to an independent. While I've seen some spinning suggesting that a double-digit swing should be viewed as a shocker for the Liberal Party even if they don't lose the seat, I think the circumstances are so unusual that they'd take a win by any margin now.
Cause of vacancy: Resignation of Malcolm Turnbull
A by-election for Wentworth has been set down for Saturday 20 October following the resignation from parliament of the former Prime Minister, Malcolm Turnbull. This post will give an assessment of how this by-election stands in history and will also comment critically on polling. As I start it on 14 Sep I won't be brave enough to predict the winner yet, but I may do so later [edit: as of the final week I am not liking the Liberals' chances of holding off Phelps at all]. This post will be updated with new polls and changed assessments through to polling day.
By-elections often produce big swings against governments, but surely 17.8% is safe? After all, there has only been one larger swing in federal by-election history (20.1% in Wakefield, 1938). In fact there are at least two reasons not to take the seat's safety for granted. These are the historic circumstances of the by-election and the prospect of losing the seat to an independent. While I've seen some spinning suggesting that a double-digit swing should be viewed as a shocker for the Liberal Party even if they don't lose the seat, I think the circumstances are so unusual that they'd take a win by any margin now.
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