Predicting 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.

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Best and Worst AFL Teams 2005 - 2015: A MoSSBOD Perspective

In the last blog on this part of the site I introduced the MoSSBOD Team Rating System, the defining characteristics of which were that it Rated teams based on Scoring Shot Production and Concession and that it provided both a Defensive and an Offensive Rating for all teams.

Today I want to explore the history of those Ratings across the last decade to see what MoSSBOD has to say about the strongest and weakest Offensive and Defensive teams across that period.

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Team Scoring Shots and Conversion Rates

In response to my earlier post on the explained and unexplained portions of game margins, Friend of MatterOfStats, Michael, e-mailed me to suggest that variability in teams' points-scoring per scoring shot - or, equivalently, teams' conversion rates - might usefully be explored as a source of unexplained variability. 

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The Dynamics of ChiPS Ratings: 2000 to 2013

Visitors to the MatterOfStats site in 2014 will be reading about ChiPS team Ratings and the new Margin Predictor and Probability Predictor that are based on them, which I introduced in this previous blog. I'll not be abandoning my other team Ratings System, MARS, since its Ratings have proven to be so statistically valuable over the years as inputs to Fund algorithms and various Predictors, but I will be comparing and contrasting the MARS and the ChiPS Ratings at various times during the season.

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Introducing ChiPS

In years past, the MAFL Fund, Tipping and Prediction algorithms have undergone significant revision during the off-season, partly in reaction to their poor performances but partly also because of my fascination - some might call it obsession - with the empirical testing of new-to-me analytic and modelling techniques. Whilst that's been enjoyable for me, I imagine that it's made MAFL frustrating and difficult to follow at times.

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What's More Important: Who You Play or Where You Play Them?

The benefits of playing at home have been extensively investigated both here on MAFL for Australian Rules football and more generally within the sports prediction community for this and other sports. Put simply, teams that play at home win more often and score more points than you'd otherwise expect them to after adjusting for the quality of the opponents they face.
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MARS Rating Changes and Scoring Percentages: 1897-2013

The idea for this blog sprang from some correspondence with Friend of MAFL, Michael, so let me start by thanking him for being the inspiration. Michael was interested in exploring the relationship between team performances and the resulting change in their MARS Ratings across a season, which I'll explore here by charting, for each team and every season, the for-and-against percentage they achieved in all games including Finals, and the change in their MARS Rating per game during that same season.
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Another View of All-Time AFL Team MARS Ratings Post the 2013 Season

Recently I'd been noticing some traffic to the site from the Big Footy website where the Forum members had been discussing the relative strengths of Bulldogs teams across VFL/AFL history. That, coupled with my continuing desire to become more proficient in the ggplot2 R package of Hadley Wickham, dragged me out of my off-season blog malaise to perform the analyses underpinning this current posting.
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How Good Are Hawthorn, How Poor GWS?

Without the benefit of emotional and chronological distance it's often difficult to rate the historical merit of recent sporting performances. MAFL's MARS Ratings, whilst by no means the definitive measure of a team's worth, provides one, objective basis on which to assess the teams that ran around in 2013.
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Current Teams' All-Time MARS Rankings

I've looked previously at the best and worst AFL teams of all time and, whilst none of the current crop of teams is vying for either of those honours as at the end of Round 11 in the 2013 season, two (GWS and Melbourne) are in the 30 lowest-rated teams ever and one (Hawthorn) is in the 50 highest-rated teams ever.
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Which Teams Fare Better as Favourites?

In this blog, the next is a series in which I've been exploring the all-time MARS Ratings I created for every game from the start of 1897 to the end of the 2012 season, I'll be looking at how well each team has performed depending on the relative strength of its opponent, as measured by their MARS Rating. So, for example, we'll consider how well Collingwood tends to do when playing a team it is assessed as being much stronger than, a little stronger than, about as capable as, and so on.
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Team MARS Ratings Performance By Decade and Overall: 1897 to 2012

In the previous blog on the topic of all-time MARS Ratings I explained the process I used to derive team Ratings across history and then identified those teams that had achieved the highest (Essendon) and lowest (Fitzroy) MARS Ratings ever. We know then which teams have burned brightest - and which flickered dimmest - across VFL/AFL history. In this blog I want to explore more extended bursts of talent or apparent lack of it.
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Measuring 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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