A curious set of Senate odds

The betting markets continue to move in Labor’s favor, and Andrew Leigh continues to tell us that they’re the most accurate predictor of results. But unnoticed by the media, one bookmaker has introduced an interesting new variant on election betting.

At Portlandbet, you can wager on the chances of minor parties winning Senate seats. In ascending order, this morning’s odds give the following probabilities of at least one minor party senator being elected in each state or territory:

(There’s no market for the Northern Territory, presumably because the chance of a minor party getting up is effectively zero.)

How realistic are these odds? Are there some opportunities for savvy election-watchers to make some money here? And what do they tell us about the likely balance of power in the Senate?

The answer to the last question is probably “not much”, because these are very thin markets. On Sunday I bet small amounts on three of the contests (a total of $55); on checking the odds this morning, those three have all moved in that direction, while the others are unchanged.

I thought the best value being offered was for a minor party to win one of the two ACT seats, which on Sunday was 6-1 against. As a result perhaps of my modest $8.50 bet, or perhaps of others who thought the same way, that’s now come in to a more realistic 9-2.

The thing to remember when it comes to Senate control, as explained in Crikey’s election guide, is that Labor and the Greens between them have to pick up three extra seats to win a Senate majority. The best chances are Tasmania, Victoria and the ACT, with a rough shot at NSW and SA.

Superficially it looks as if Portlandbet has got it the wrong way around, giving the Greens less of a chance in Victoria than in WA and NSW. But presumably whoever set the odds is thinking that in those latter two states the Greens could get up at the expense of the third Labor candidate. The way Labor is travelling in the polls, that’s a pipe dream.

By far the most likely outcome is that in NSW, WA and Queensland, Labor and the Coalition will split the seats three-all, locking out the minor parties. South Australia will probably be the same, although the Coalition is doing so badly there that Family First or even the Democrats could snatch their third seat.

In a month’s time, when some money has flowed in, these odds might be a worthwhile guide to the outcome. For now it’s more a matter of curiosity value.