Line Betting : A Codicil

While contemplating the result from an earlier blog, which was that home teams had higher handicap-adjusted margins and won at a rate significantly higher than 50% on line betting - virtually regardless of the start they were giving or receiving - I wondered if the source of this anomaly might be that the bookie gives home teams a slightly better deal in setting line margins.

A Line Betting Enigma

The TAB Sportsbet bookmaker is, as you know, a man to be revered and feared in equal measure. Historically, his head-to-head prices have been so exquisitely well-calibrated that I instinctively compare any model I construct with the forecasts he produces. To show that a model historically outperforms leads me to scuttle off to determine what error I've made in constructing the model, what piece of information I've used that, in truth, was only available with the benefit of hindsight.

MAFL 2010 : Round 18

If the Recommended Portfolio is to make a bid for profitability I've a feeling that this weekend needs to be the start of it.

Final Ladder Positions: Simulations After Round 17

If you're a Pies, Dogs or Carlton supporter - or, I guess, an Eagles supporter with a contrarian nature and a willingness to profit from adversity - you've much to be happy about following last weekend's results and their effect on your team's chances of participating come September.

MAFL 2010 : Team Dashboard for Round 17

Here's the MAFL Team Dashboard for Round 17:

MAFL 2010 : Round 17 Results

Once the Roos had lost narrowly to the Dons on Saturday, Investors with the Recommended Portfolio needed the remaining four results to go their way to finish the weekend in the black. Carlton's second-half rejuvenation a little later on Saturday put paid to any such hopes so that, despite a perfect set of outcomes on Sunday, the Portfolio still dropped in value by a little under 1.4% across the weekend.

Finding Value in the Markets for Final Ladder Positions

In an earlier blog I used a simple method to create one view of the season's final home-and-away ladder.

Those projections had Collingwood finishing third because it lost narrowly to the Cats in Round 19 while the Cats and the Saints were projected to win all their remaining games. Three of the Cats' wins and two of the Saints' were by only a handful of points, however, so it was easy to imagine scenarios in which the ordering at the top was quite different and where, for example, the Pies finish top of the ladder.

MAFL 2010 : Round 17

First, some good news.

Back in Round 14, Investors in the Recommended Portfolio had a line bet on the Saints, who played Melbourne at Dockland. In the Bet Summary for the week I had the Saints giving the Dees 35.5 points start, which meant that their eventual 100-65 victory was a half-point short of covering the spread, a fact that I seem to recall lamenting at some length, certainly in the conversations that I had in the following week, and probably in the blog too (which I'm not of a mind to review at the moment).

Projecting the Final Ladder for 2010 (After Round 16)

It's late July and normally it'd be time for the first whispers of tanking to emerge, but the rejigging of the draft process next year to accommodate the introduction of Gold Coast and GWS has significantly reduced the reward to sustained ineptitude so effectively that, this year, I doubt there'll be much talk of it (or, come to that, much compelling evidence of its existence).

MAFL 2010 : Team Dashboard for Round 16

Here's the MAFL Team Dashboard for Round 16:

MAFL 2010 : Round 16 Results

If ever you wanted evidence to support the aphorism that it's unwise to pre-emptorily enumerate your poultry, Sunday afternoon's Fremantle v Melbourne game is it.

The Importance of a Team's Recent Form: What Bookies (and MARS) Think

When the TAB Sportsbet bookie is framing a market for an upcoming game, clearly one set of data that he uses is the recent results of the participating teams. This raises two questions:

• What proportion of the variability in bookie prices can be explained solely by recent results?
• What relative weighting does the bookie ascribe to each previous game?

Super Smart is Taking Heed of Bookies

Across a series of blogs now we've explored the Super Smart Model (SSM) and investigated its ability to predict victory margins. In this blog we'll look more closely at which variables most influence SSM's forecasts.

Trialling The Super Smart Model

The best way to trial a potential Fund algorithm, I'm beginning to appreciate, is to publish each week the forecasts that it makes. This forces me to work through the mechanics of how it would be used in practice and, importantly, to set down what restrictions should be applied to its wagering - for example should it, like most of the current Funds, only bet on Home Teams, and in which round of the season should it start wagering.

MAFL 2010 : Team Dashboard for Round 15

Here's the MAFL Team Dashboard for Round 15:

MAFL 2010 : Round 16

Faced with six home team favourites Investors could easily have been facing another dose of high risk, low potential return wagering this weekend, but a combination of moderate wagers on the two at-home underdogs and larger wagers on some of the more attractively priced at-home favourites has resulted in a far more balanced portfolio of wagers, at least for those with the Recommended Portfolio.

Simplifying MARS Rating Updates: An Epilogue

In my previous blog I used Eureqa to find a simpler version of the equations for updating MARS Ratings.

There I jumped straight to what I deemed the 'best' solution that Eureqa had found, glossing over a slew of perfectly adequate and much simpler solutions that it also found.

MARS Ratings Revisited: There Must Be a Simpler Way

It's official: Eureqa is an amazing tool.

With all the recent model-building I've been undertaking and writing up here in various blogs, I've become more aware of the predictive power of MARS Ratings.

Predicting Head-to-Head Market Prices

In earlier blogs I've claimed that there's not much additional information in bookie prices that's useful for predicting victory margins than what can be derived from a statistical analysis of recent results and an understanding of game venues.

We saw that the Smart Model - which makes its victory margin predictions using only team MARS Ratings, a team's two most recent results and information about whether or not the relevant game is being played interstate from the point of view of one of the participants -performed about as well as the best model that can be built using bookmaker prices, where performance is measured on any of a number of sensible metrics.

MAFL 2010 : Round 15 Results

For most Investors it was another weekend of nibbling away at the season's deficit.

Carlton's loss on Sunday evening meant that, for those with the Recommended Portfolio, the nibble was only a nip, but a couple of percent is undeniably better than an ocular prod with a dulled wooden implement.

The Relationship Between Head-to-Head Price and Points Start

I've found yet another MAFL-related use for the Eureqa tool, this time to determine the precise relationship between a team's head-to-head price and the start it's giving or receiving on line betting.

Building The Super Smart Model

In a previous blog we investigated the information content of bookie prices in the context of predicting the victory margin of a game.

What Do Bookies Know That We Don't?

Bookies, I think MAFL has comprehensively shown, know a lot about football, but just how much more do they know than what you or I might glean from a careful review of each team's recent results and some other fairly basic knowledge about the venues at which games are played?

MAFL 2010 : Round 15

Investors face a far less breathtaking set of wagers this weekend.

In fact, they can take a complete breather until Saturday since none of the Funds have any interest in Friday night's Port v Collingwood game, despite Port playing at home and being priced at $5.00 head-to-head and +32.5 points on line betting.

MAFL 2010 : Team Dashboard for Round 14

Here's the MAFL Team Dashboard for Round 14:

MAFL 2010 : Round 14 Results

Well that was a good weekend's wagering no matter how you dissect it.

What prevented it from attaining 'fantastic' status was the mercy shown by the teams occupying 1st and 2nd on the table, each of which slacked off in the latter parts of their respective games leading to our losing one line bet (on the Cats) by 4.5 points and the other (on the Saints) by just half a point.