2014 - Round 15 : Head-to-Headless

The absence of any Head-to-Head bets has brought about a slight reduction in the aggregate volume of wagering this week, though the Margin Fund has made up for some of the difference by increasing its level of activity to 10 bets for the round. That feels a little like turning up at the Globe Theatre and being informed that the role of Lady Macbeth will tonight be performed by Kermit the Frog.

Our inactivity in the Head-to-Head market is not especially surprising though because, with the prices on offer in the market and the rules constraining its wagering activity to home teams priced at $1.50 or more, the Head-to-Head Fund had only four teams to consider this week. It found none of them worthy of its affection, rating the $5.75 Saints and the $6.00 Lions as only about 7% chances of victory, the $1.60 Dogs as only 53% chances, and the $3.25 Crows as only 24% chances, making each of these teams loss-making prospects in the eyes of the Fund.

The Line Fund is as active this week as it was last week, venturing six wagers on home teams, three favourites and three underdogs, offering or receiving between about one and seven goals start. The Margin Fund has opted for 10 wagers on five teams, four more than last weekend and all of them home team favourites - as they almost always will be if they're to be the subject of Margin Fund wagers.

(For the second week in a row, the TAB Bookmaker has delayed posting a SuperMargin market for the Fremantle game. For the purposes of this blog I've assumed we'll get $7 prices for the two margin ranges we're after. I'll update this blog once I know whether or not that's what transpired.

UPDATE: We got prices of $8 and $7. The updated Ready Reckoner entry for the Fremantle game appears at the end of this blog.)

In total then we've 16 wagers this week spanning all nine home teams and representing 17% of initial Recommended Portfolio Funds. That's down by about 1% point on last week.

Sydney and Hawthorn carry the week's greatest upside of 3.3c, which Hawthorn will realise if it wins by 33 to 39 points, and Sydney will deliver if it wins by 43 to 49 points. Any of the Saints, the Lions, the Dogs or the Crows could provide a 2.3c gain by prevailing in their respective Line markets.

Maximum downside of almost 3c also rests with the Hawks and the Swans, which either of them could precipitate through winning by less than 30 points. The same four teams that carry the second tier of upside - the Saints, Lions, Dogs and Crows - also control the second tier of downside, which this week amounts to a 2.5c loss.

Total upside for the week is +19c and total downside is -17c.


This week sees contention amongst the Head-to-Head Tipsters in any significant quantities only for the Geelong v Essendon game, where the underdog Dons are favoured 15-13, and in the Collingwood v Carlton game, where the Pies enjoy Bookmaker favouritism and 17-11 support amongst the Tipsters. There are token levels of disagreement in other contests but in none does it amount to more than four dissenting voices.  

Home Sweet Home is again the round's most eccentric Tipster, differing on average in every game with about one half of the other Head-to-Head Tipsters. Easily Impressed I is second-most eccentric with a Disagreement Index of 37%, and Silhouette is third with an Index of 27%. C_Marg is amongst the least different of Head-to-Head Tipsters this week with an Index of only 17%.

Margin Predictors lie on either side of zero in four contests, most dramatically in:

  • the Geelong v Essendon game where predictions range from a 37 point Cats win, according to C_Marg, to a 5 point Dons win, according to some of the H2H Predictors,
  • the Fremantle v West Coast game where Combo_NN_2 has Freo winning by 43 points and the two Win and two ProPred Predictors have the Eagles winning by 2 points,
  • the Collingwood v Carlton game where Combo_NN_1 has the Pies winning by 43 points, and H2H_Adj_3 and ProPred_3 have the Blues winning by 2 points.

The fourth game in which there's a dissenting Predictor is the Dogs v Dees game where Combo_NN_2 is alone in predicting a Dees victory. Combo_NN_2 and Combo_NN_1 are the Predictors that are at the extremes in most games this week, assuming that position in three games each. As a consequence, these two have the round's largest Mean Absolute Deviation from the all-Predictor averages. Bookie_3 and Win_7 are the Predictors that are next-most often at the extreme of predicted margins, a position they've assumed in two games.

In three of the four games where the Margin Predictors span either side of zero, the Head-to-Head Probability Predictors also sit either side of 50%.

In the Geelong v Essendon game, estimates of the Cats' chances range from 42% to 86%, in the Fremantle v West Coast game, estimates of Freo's chances range from 46% to 80%, and in the Collingwood v Carlton game, estimates of the Pies' chances range from 47% to 79%.

WinPred is at the extreme in one of those contests - it's the Predictor rating Freo as 46% chances - and in four other contests besides, which puts it in this position in one game more than C_Prob and H2H, both of which are at the extreme in four games. Despite being extreme in one fewer game that WinPred and in the same number of games as H2H, C_Prob has still managed to produce the week's largest MAD at 8.2% points per game. ProPred has the second-largest MAD of 8.1% points per game.

The Line Fund algorithm has been sharper still (ie nearer 0 and 1) in its probability assessments this week, rating West Coast as 80% chances, Essendon as 74% chances, Carlton as 70% chances, Adelaide as 69% chances, Hawthorn as 68% chances, St Kilda as 66% chances, the Dogs as 62% chances, and Sydney as 61% chances, leaving the Lions as the only team it rates as winning on Line betting but with a less than 60% chance of doing so. A highly negative probability score is, therefore, a real possibility for the algorithm this week, as is a moderately large probability score.


ChiPS has again this week been heavily influenced in its margin predictions by the Ratings Differences in each contest, the correlation between these Differences and the predicted victory margins coming in at +0.96.

Only two teams are recommended by ChiPS for wagering at the current prices: Geelong at $1.33, and St Kilda, barely, at $5.75.

UPDATE The Ready Reckoner for the Fremantle v West Coast game based on the prices actually secured appears below.