Inferring 2015 Grand Final Prices
/This time of year it's always fun to consider what the current wagering markets imply about the likely Grand Final prices.
Read MorePredicting Bookmaker Head-to-Head Prices : Five Years On
/Recently, in light of the discussions about the validity of the season simulations written up over on the Simulations journal, I got to thinking about modelling the Bookmaker's price-setting behaviour and how it might be expected to respond to the outcomes of earlier games in the season. It's a topic I've investigated before, but not for a while.
Read MoreMapping Expected Margins to Probabililties
/I'm a sucker for a colourful chart, and today's is based on simulations using an earlier model of Home and Away team scoring, constrained by bookmaker-based empirical realities.
Read MorePredicting Total Game Scores Versus Predicting Margins
/In the comments section of the previous blog, LT pointed out that Bookmakers seem to be doing a better job this year predicting the sum of the Home Team and Away Team scores than predicting the difference between them.
Read MoreSame Head-to-Head Prices, Different Lines
/I've raised an eyebrow or two more than once when I've seen the TAB bookmaker post two markets with the same head-to-head prices but different line market handicaps priced at even-money.
Read MoreOverround: The Bookmaker's Bank Fee
/I was updating the MAFL Fund Performance page last evening and found myself pondering the topic of bookmaker overround.
Read MoreSuperMargin Implications? Yes, They Are Atrocious.
/In a recent blog I developed an empirical model of AFL scoring in which I assumed that the Scoring Shots generated by Home and Away teams could be modelled by a bivariate Negative Binomial and that the conversion of these shots into Goals could be modelled by Beta Binomials.
Read MoreThe 2014 Seasons We Might Have Had
/Each week the TAB Bookmaker forms opinions about the likely outcome of upcoming AFL matches and conveys those opinions to bettors in the form of market prices. If we assume that these opinions are unbiased reflections of the true likely outcomes, how might the competition ladder have differed from what we have now?
Read MoreModelling Team Scores as Weibull Distributions : Part II
/In a previous post I discussed the possibility of modelling AFL team scores as Weibull distributions, finding that there was no compelling empirical or other reason to discount the idea and promising to conduct further analyses to more directly assess the Weibull distribution's suitability for the task.
Read MoreThe Responsiveness of Bookmaker Prices To Winning and Losing
/In this blog I'm seeking to answer a single question: how are a team's subsequent head-to-head bookmaker prices affected by the returns they've provided to head-to-head wagering on them in recent weeks? More succinctly, how much less can you expect to make wagering on recent winners and how much more on recent losers?
Read MoreThe Ten Most Surprising Things I've Learned About AFL So Far
/The last few months have been a generally reflective time for me, and with my decision to leave unchanged the core of MAFL algorithms for 2014 I've been focussing some of that reflection on the eight full seasons I've now spent analysing and predicting AFL results.
Read MoreThe Relative Importance of Class and Form in AFL
/Today's blog is motivated by a number of things, the first of which is alluded to in the title: the quantitative exploration of the contributions that teams' underlying class or skill plays in their success in a given game relative to their more recent, more ephemeral form. Is, for example, a top-rated team that's been a little out of form recently more or less likely to beat a less-credentialled team that's been in exceptional form?
Read MoreBookmaker Overround: A General Framework
/Previously I've developed the notion of taking a Bookmaker's prices in the head-to-head market and using them to infer his opinion about the true victory probabilities of the competing teams by adopting an Overround-Equalising or a Risk-Equalising approach. In this blog I'll be summarising and generalising these approaches.
Read MoreTeam Ratings, Bookmaker Prices and the Recent Predictability of Finals
/Last weekend saw three of four underdogs prevail in the first week of the Finals. Based on the data I have, you'd need to go back to 2006 to find a more surprising Week 1 of the Finals and, as highlighted in the previous blog, no matter how far you went back you wouldn't find a bigger upset than Port Adelaide's defeat of the Pies.
Read MoreThe Predictability of Game Margins
/In a recent blog post I described how the results of games in 2013 have been more predictable than game results from previous seasons in the sense that the final victory margins have been, on average, closer to what you'd have expected them to be based on a reasonably constructed predictive model. In short, teams have this year won by margins closer to what an informed observer, like a Bookmaker, would have expected.
Read MoreSimulating SuperMargin Wagering
/Season 2013 has been a good one, so far, for SuperMargin wagering, which led me to ponder why that might be the case. More generally, I wondered if we could define the characteristics of a season and of the predictive algorithm that we're using for selecting wagers, which are most propitious for this form of wagering.
Read MoreYet Another Look at Bookmaker Overround
/Lately I've been pondering the challenge of determining how much overround the TAB Bookmaker has embedded in the head-to-head prices of each team in an AFL contest.
Read MoreDetermining Bookmaker Implicit Probabilities: The Risk-Equalising Approach
/In the previous blog I developed a new way of divining a bookmaker's probability assessments of the two teams by assuming that he believes his maximum calibration error - the (negative) difference between his probability assessment for a team and its true probability of victory - is the same for each team in percentage point terms, and that he levies overround on each team's price so as to ensure that it will still deliver an expected profit even if his probability assessment is maximally in error.
Read MoreMeasuring Bookmaker Calibration Errors
/We've found ample evidence in the past to assert that the TAB Bookmaker is well-calibrated, by which I mean that teams he rates as 40% chances tend to win about 40% of the time, teams he rates as 90% chances tend to win about 90% of the time and, more generally, that teams he rates as X% chances tend to win about X% of the time.
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