Is That A Good Probability Score?
/Each week over on the Wagers & Tips blog, and occasionally here in the Statistical Analysis blog I use probability score as a measure of a probability predictor's performance.
Read MoreGame Statistics and Game Outcomes
/My first Matter of Stats blog looked at how game statistics, averaged across an entire season for each team, are predictive of key season outcomes like ladder position, competition points and MARS Ratings.
This post summarises similar analyses, but here performed on a per-game basis
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 MoreGame Statistics and the Dream Team
/Today, a new voice comes to MAFL. It's Andrew's. He's the guy that uncovered the treasure-trove of game statistics on the AFL website and he's kindly contributed a blog taking you through some of the analyses he's performed on that data. Let me be the first to say "welcome mate".
I have lurked on the sidelines of MAFL and Matter of Stats for a couple of years and enjoyed many conversations with Tony about his blogs. I found myself infected with curiosity and so, with gratitude to Tony, here's my newbie blog post.
Read MoreCurrent 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.
Read MoreEfficacy of Game Statistics for Wagering
/In a previous blog, I explored 23 team summary game statistics that are provided by the AFL - statistics such as disposals, one percenters, clangers, and so on - to see which, if any, of them, might help to predict game outcomes.
Read MoreDo Bookies Undervalue Team Performance Metrics?
/In 2003 Michael Lewis' Moneyball was published, in which he related the story of Billy Beane, Oakland A's General Manager, and his discovery that the market for baseball players mispriced particular skills. Some skills that could be shown, statistically, as being associated with greater team success weren't recognised as valuable (for example, getting on base, as measured by On-Base Percentage), while other skills were over-valued because of an historical belief that they were related to success (for example, batting in runs, as measured by RBI).
Read MoreReally Simple Proves Remarkably Effective
/The Really Simple Margin Predictors (RSMPs), which were purpose-built for season 2013, have shown themselves to be particularly accurate at forecasting game margins. So much so, in fact, that they're currently atop the MAFL Leaderboard, ahead of the more directly Bookmaker-derived Predictors like Bookie_3 that have excelled in previous years.
Read MoreThe Value of MARS Ratings Points Across Time Revisited
/When last I considered the issue of the value of MARS Ratings across time I assessed their value in terms of a team's victory probability. Perhaps a more intuitive approach would be to, instead, value them in terms of a team's victory margin.
Read MoreOn The Randomness of Final AFL Scores
/You'd be forgiven for assuming that the last digit of a team's final score in an AFL contest was essentially random - in other words that it was as likely to be a 0 as a 1, a 4 or a 9.
Read MoreMeasuring the Surprise in a Season's Results
/In the previous blog we looked at the average level of surprisals generated by teams and by team pairings across all of VFL/AFL history and during the most-recent seasons. Today, as promised in that blog, I'm going to analyse surprisals using the same general methodology, but by season.
Read MoreWhich Teams Are The Surprisal Packets?
/Anyone who's ever tipped sporting outcomes knows the frustration of the untippable team, the team that win when they're supposed to lose, and lose when they're supposed to win. With that idea in mind, which team's results, I wondered, have been the most difficult to predict across the history of the VFL/AFL.
Read MoreThe Value of MARS Ratings Points Across Time
/As we look at MARS Ratings across the expanse of VFL/AFL history, one thing we might want to consider is whether the value of a Rating Point has remained stable across those 13 decades. I've assumed, implicitly, that this is the case in the interpretations I've made of recent analyses, for example about the game's greatest upsets, but there's no a priori reason for this to be the case.
Read MoreWhich 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.
Read MoreThe Greatest Upset Victories in VFL/AFL History (1897-2012)
/The Suns' victory over the Saints in the first round of the 2013 season was heralded as an "upset win" for the Suns and one of the greatest in their short history. Undoubtedly their win was unexpected, but even the bookmakers rated the Suns as only $3.75 chances, so it was hardly a Halley's comet-like occurrence.
Read MoreTeam 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.
Read MoreAnd the Best and Worst VFL/AFL Teams of All-Time Are ...
/I've promised for a while now to create MARS Ratings for the entire history of the VFL/AFL and with some time away from home over Easter, I'm now able to deliver on that promise.
Read MoreReally Simple Margin Predictors
/Sometimes it's interesting to see where an idea takes you.
This blog started out as a wet weekend's musing: how predictive might a margin predictor be if it was based on a single variable?
Read MoreAre the Victory Margins for Some Games Harder to Predict than for Others?
/It's unarguable that the winner of some games will be harder to predict than the winner of others. When genuine equal-favourites meet, for example, you've only a 50:50 chance of picking the winner, but you can give yourself a 90% chances of being right when a team with a 90% probability of victory meets a team with only a 10% chance. The nearer to equal-favouritism the two teams are, the more difficult the winner is to predict, and the further away we are from this situation the easier the game is to predict.
Read MoreClustering Your Way To Line Betting Success : Building a Predictive Model
/In the previous blog I used a clustering algorithm - Partitioning Around Medoids (PAM) as it happens - to group games that were similar in terms of pre-game TAB Bookmaker odds, the teams' MARS Ratings, and whether or not the game was an Interstate clash. There it turned out that, even though I'd clustered using only pre-game data, the resulting clusters were highly differentiated with respect to the line betting success rates of the Home teams in each cluster.
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