Sunday, September 19, 2010

MAFL 2010 : Round 25 Results (Week 3 of the Finals)

As predicted, the haloed and the winged triumphed over the furry this weekend, leaving us with a Pies v Saints Grand Final for only the second time in VFL/AFL history.

Presumably there are supernatural consequences of cursing saints, but it was difficult to avoid risking them on Saturday night if you were a MAFL Investor watching the game as the Saints went marching off and allowed the Dogs to tack on just enough late points to win on line betting by half a point.

That cost the Recommended Portfolio almost 1% and meant that it increased by only 2.2% over the two games. This leaves the Recommended Portfolio down by 6.4% on the season on the back of three straights weeks of profitability during the Finals.

MIN#017's Portfolio also climbed for the third successive week, this time by 9.1% to leave it down by 42.4% for the season. MIN#002's Portfolio remained unchanged at 72c.

Here's the Dashboard for Round 25:



On MARS Ratings, the two weekend winners both swapped places with the losers, which slips the Pies into 1st and the Cats into 2nd, and the Saints into 3rd and the Dogs into 4th.

Once again all tipsters picked both winners this weekend. Chi and ELO recorded the best Mean Absolute Prediction Errors (MAPEs) of 15 points per game, while HAMP managed 18, BKB 20, and LAMP 21.5. These high levels of accuracy produced reductions in the season-long MAPEs for all Margin Tippers but left their ordering unchanged.

BKB remains 1st on 29.56 points per game, ahead of LAMP on 29.98 - the first time it's been below 30 since Round 19 - and HAMP on 30.11.

Surprisingly, neither HAMP's not LAMP's excellent MAPEs would have translated into line betting success this season. HAMP's only been 46% accurate in selecting the correct line winner and LAMP's only been 49% accurate. In comparison, ELO's been right almost 55% of the time.

The Median APE metric has been no better at predicting line betting performance, since LAMP retains outright leadership on this measure with a score of 26 points. ELO knocked half a point from its Median APE this week to draw it level with BKB on 26.5 points and in joint 2nd place.

What's been the source of ELO's superior line betting accuracy in comparison to HAMP, LAMP and Chi (his accuracy is only 47%)? Being right more often in those games that were closer in terms of line betting it turns out, as the following graphic shows.



The rows in this graphic are based on the size of the absolute handicap-adjusted margin - the number that you get when you subtract the away team score from the home team score, add the home team handicap and then take the absolute value. For example, the absolute handicap-adjusted margin for a game that finishes 100-75 where the home team was giving 30.5 points start is 5.5 points, which is the absolute value of 100-75-30.5.

In line betting terms, therefore, the closest games are those on the first row of the table, and games become less close as we move down the rows.

Each pie reflects two things:
  • the proportion shaded black represents the accuracy of the particular Margin Tipper for games within the range of actual absolute handicap-adjusted margins described by the row
  • the size of the pies within each row is proportional to the number of games that have finished with that particular range of actual absolute handicap-adjusted margins
Now focus on ELO's column. You can see that it's done well relative to the other Margin Tippers in those games that finished with an absolute handicap-adjusted margin under 24 points - in fact, it's the only Margin Tipper with a better than 50% record for these games - and that it's been particularly accurate in those games that finished with an absolute handicap-adjusted margin of 24 to less than 36 points.

In those games that finished with an absolute handicap-adjusted margin of 36 points or more, which have been the most frequent type of games this season, it hasn't been especially accurate, but no less so that the other Margin Tippers.

This week, in terms of home-and-away ladder positions, we saw 1st defeat 2nd and 3rd defeat 4th. Historically, teams from 1st and 2nd have now performed equally well in the 3rd week of the Finals, appearing 11 times each for 8 wins and 3 losses.

Teams from 3rd, however, have a much better record than teams from 4th, though they've appeared in the Semis on two fewer occasions. Third-placed teams now have a 44% record of proceeding to the Grand Final, while fourth-placed teams have only an 18% record.



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