By-election? More like BYE-election!

Yes, it's the final week of yet another by-election, this time as federal Parliament says farewell to former Prime Minister Turnbull. Much of the commentary around the seat of Wentworth has discussed Mr Turnbull's personal support, noting the less-known Dave Sharma will lack the support that the former representative held while suffering something of a backlash for his party's ousting of yet another sitting PM. The polling certainly seems to reflect this, with the normally indomitable two-party margin of 17.75% into dangerous territory, particularly with the emergence of a popular independent candidate. However, this is a generalisation. This polling is possibly the most erratic and least conclusive data set I have had to work with in the 8+ years I've been making these predictions. At the same time, the unique situation behind this by election would make an examination of the history of Wentworth an almost futile activity.

An Almost Futile Activity

Wentworth was one of the original 1901 electorates and was first held by the Free Trade Party. The FTP became the Anti-Socialist Party, then merged with the Protectionists to become the Commonwealth Liberal Party in 1909. Wentworth went along for the ride, and stayed with the CLP until it also went through a merger to become the Nationalist Party in 1917. The Nationalists then merged to become the United Australia Party in 1931, although Wentworth came the long way round, with Walter Marks going through two bouts of Independent-ness and a short stint in the Australian Party between being a Nationalist and a member of the UAP. In 1945 the United Australia Party was replaced by Menzies' Liberal Party.

Sir Eric Harrison held the seat as the first official Liberal candidate until 56 when he was replaced by the Liberal's Les Bury. Liberal Bob Ellicott took over in 1974 until 1981 when the Liberal Party's Peter Coleman won the seat. In 1987 Wentworth passed to the eventual leader of the Liberal party, John Hewson, who held for two years after his party's 1993 electoral defeat. Andrew Thomson, a Liberal     Party member, held the seat after that, and then in 2001 the Liberals' Peter King won the seat. In 2003 King was successfully challenged by Malcolm Turnbull for pre-selection, who went on to win the seat for the Liberal Party in 2004. The seat has been in Liberal hands ever since.

 

In essence, you could call Wentworth a safe Liberal seat, having been held by the party since 1901--quite an achievement for a party that wasn't founded for another four and a half decades. Labor has come close to taking the seat a couple of times, most narrowly in the 1943 election where an ALP landslide saw the Labor party go from 4 seats down to a 26 seat lead, and most recently in the 2007 Rudd-slide.

The Curse of being Too Strong

As normally calculated, the concept of a safe seat is flawed by its preoccupation with the two-party data, which is based on assumptions of voting behavior which are becoming less and less reliable in modern Australia. The recent by-election in Mayo's return of Centre Alliance candidate Rebekah Sharkie is a good example of this, where a historically strong Liberal seat was harmed by its own dominance. The ALP vote in Mayo was (both this year and in 2016) lower than the (so-called) third-party candidate. Where a third-party candidate is not ideologically affiliated with either major party (unlike, say, the Australian Conservatives or the Greens) and that third-party drops out in the count, their votes generally divide between the two major parties in a broadly similar pattern to the primary vote for those parties. Where the supposed "third-party" actually outlasts a major party in the count, however, the major party vote almost entirely flows, for partisan reasons, against the other major party. This means "safe" seats are actually the most vulnerable to independent candidate incursions.

In Wentworth, the much-touted third option is independent Kerryn Phelps. If Kerryn drops out before the ALP, most of her votes will presumably follow the historic sentiment of Wentworth and back the Libs. If, however, she out-polls the ALP, she will reap the lion's share of ALP support which will almost certainly guarantee her win. With a majority of one seat in the House of Representatives, the Liberals desperately need to hold on to Wentworth, and thus it is paradoxically in Labor's best interests nationally to poll lower than Cr Phelps.

The Polls! The Polls!

With this in mind, what to the numbers so far show? Will Phelps out poll the ALP to take victory, or fall short keeping the nation's second smallest seat in Liberal hands?

Obviously the Liberal primary vote is a pretty solid leader, but at around 40% certainly not enough to see off a challenge from the combined remaining vote. The real question is whether Phelps will beat the ALP, scooping up the bulk of the non-Lib vote and winning, or whether the ALP will beat Phelps and see the vote scatter between the major parties pushing the Libs over the line. And on this data it's really unclear who will come out ahead in that race.

Normally the largest part of the Greens vote flows ultimately to the ALP, but that's far from certain in this race, especially with key Greens issues like LGBT rights playing well into Cr Phelps' platform. Instinctively the "other" vote might be seen as a rejection of both major parties a-pox-upon-both-your-houses style, which is promising for Phelps too, but it also includes the "undecided" category so that's not necessarily true.

The Prediction

The latest data has Phelps ahead of the ALP in her own right. I'm going to go out on a limb and assume she will also benefit the most from the Other and Greens votes to maintain this lead. The ALP-Phelps vote combined roughly rivals that of the Liberal candidate.

On those assumptions, Kerryn Phelps would be elected the new member for Wentworth.

TL;DR: Wentworth is a safe Liberal seat, and has been since federation. If Labor beats independent candidates Phelps enough of her vote will go to the Liberals to win the seat. I am expecting Phelps to outlast the ALP, however, and reap the majority of their preferences to win the seat.