2012 Finals Week 2 - Wagers & Tips : Flat Line But Head-to-Head and Margin in Both

Again this week the Line Fund has taken one look at the starts the home teams are being forced to give by the TAB Bookmaker and has opted to keep its - well, our - money in its pocket. The Head-to-Head Fund, meantime, likes the prices that this same Bookmaker is offering for the Crows and the Pies head-to-head, and the Margin Fund is willing to put money, at $7.50, behind its predictions of narrow wins by both home teams, so Investors nonetheless find themselves with plenty to be concerned about on Friday and Saturday, regardless of the Line Fund's indifference.

These two pair of wagers, of similar size at similar prices and in the same SuperMargin buckets in both games, make for a Ready Reckoner that looks like the result of a poorly-funded and oddly-directed cloning project.

The various Tipsters and Predictors all agree that the Crows and the Pies should be favourites, though the Predictors vary considerably in terms of the level of confidence with which they hold this view. Amongst the Margin Predictors, Win7, for example, thinks that the Crows will win by almost 5 goals, while Combo_NN1 feels they'll win by only slightly more than a single goal. Amongst the Head-to-Head Probability Predictors, the TAB Bookmaker (implicitly) rates the Crows as about 59% chances, while WinPred rates them as 85% chances.

In the other game, Win7 is again the home team optimist, tipping the Pies to win by 17 points, with Combo_NN1 this time the home team pessimist, tipping them to win by only a single point. WinPred and the TAB Bookmaker are once more the book-ending Probability Predictors, rating the Pies as 74% and 55% chances respectively.

The Line Fund algorithm rates both games as near coin-tosses once the handicaps are factored in, which is why it's opted to refrain from wagering once again this week.

On the right is a table that summarises the calibration of the Line Fund algorithm's probability assessments for each team so far this season. It provides the average probability score for all the games in which a team has been a participant, either as the home or as the away team, and is calculated for a particular team as 1+log(Prob(Team Wins on Line Betting)) when the team wins on line betting, and as 1+log(1-Prob(Team Wins on Line Betting)) when the team loses on line betting. In both cases, the logs are calculated to the base 2, so the unit of the probability score measure is bits. 

With this method of calculation, attaching a probability greater than 50% to a team that wins on line betting will result in a positive probability score, and attaching a probability less than 50% to a team that wins on line betting will result in a negative probability score.

I've highlighted with a dark border those four cells that are relevant to this week's contests and, on the basis of this, now feel more comfortable that the Line Fund has opted to pass on this week's wagering opportunities. It's clear that the Line Fund has done poorly so far this season is assessing the chances of Adelaide and Collingwood on line betting when playing at home, and on Fremantle and West Coast when playing away from home.

(But, logically, if the Line Fund's been poor at assessing the chances of these teams in these circumstances, then maybe we should be wagering when the Fund says we shouldn't ...)

To me, it's interesting to note that there is no team this year for which the Line Fund has a positive average probability score when playing home and away, but seven teams for which the Fund has a negative average probability when playing home or playing away. As well, there are only seven teams for which the overall average probability score, home and away, is positive, and none for which the average is above 0.04. It's also very clear that the Fund has generally struggled to assess the chances of the Crows, Blues, Dees and Port on line betting.