Timeplotting Betfair data

Betting odds are a great (if not the greatest) indicator of future truths.

Most online betting companies operate live markets that are left open to new bets as the event is taking place. For example, last weekend you could still bet on Andy Roddick to win Wimbledon right up until the final point of the final game, the odds growing smaller and smaller as his chance to win grew ever more impossible.

This data about the truth can tell a fascinating retrospective story about the market. If there’s a lot of market movement during the game, with odds fluctuating between the eventual victor and loser, the event could be deemed more exciting as the collective wisdom couldn’t make up their minds as to who was going to win, the outcome only being discovered in the dying moments of the match.

In the dullest matches the odds flat-line, showing little movement in any direction or very quickly favouring one team over the other.

Similarly, points of high drama (a sending off in rugby, a tie break in tennis…) tend to swing the markets rapidly in one direction or another for a short period of time as the crowd herd towards a particular outcome.

So, if we have data that can determine competitiveness and amount of drama in a sporting event then these are at least two of the prerequisites that determine whether something is worth watching on the various online catch-up services. Furthermore, now that iPlayer can link to time segments within a show, the betting data could be also be used to provide indexes to key moments in a match.

I thought it would be fun to log the live market movement of the 2009 Women’s singles final every few seconds to see what story it would tell. The image below uses timeplot from the MIT SIMILE project, showing each player’s odds along the y-axis and time along x-axis,

demo here (requires html canvas support)

The red line shows Venus the clear favourite (with lower odds on the y-axis) right up until the first set tie break at 3pm after which the odds were reversed as the match gradually slipped away from her over the next half-an-hour. It was an exciting match for an hour or so.

Looking at the corresponding BBC Sport live text reports there were two moment of drama. The first around 30 minutes in to the match can be seen obout a third of the way along the timeplot, where Serena’s odds jump sharply up for a couple of minutes. Here’s the BBC Sport notes from around that time,

14:38 Venus *4-4 Serena Venus ramps up the power on her return, jumping out to a 30-0 lead, and peppering the baseline with some ferocious groundstrokes, she earns two break points. Serena’s second serve kicks up viciously to force the error, before lil sis comes galloping to the net. Venus misses by inches with the pass and Serena comes through with two aces on the trot.

It seems to describe the first important moment in the match, Serena nearly losing her serve.

The other obvious change in the time series, at 3pm, where the market swings rapidly between the two possible outcomes is again described by the BBC,

15:02 Venus 6-7 (3-7) Serena Serena nudges ahead, a rocketing forehand making Venus net for 3-1. HawkEye challenge on the next point, but Venus’s backhand brushes the baseline. A crunching off-forehand means Serena swaps sides at 4-2. At 5-2, Serena comes up with a brutal combination of groundstrokes, finding the angle to wrong-foot Venus - leaving her sister on the ground. Serena doesn’t see that, she has turned around and is pumping her fist. She misses the first set point but then produces a stunning, stunning backhand lob to claim it. More fist-pumping. Brilliant stuff from the younger Williams.

After that the odds diverge to the extent where the match is effectively over 15 minutes before the last point.

It would be neat if I could link the timeline up to the time stamps in archived Wimbledon final on iPlayer so that people could dip in and watch the clips of these two important moments - bbc.co.uk/i/p003n7bt/?t=25m30s - but it doesn’t seem the feature is enabled for that video.

You can get the time series data yourself, as well as download the betfairfree project that generated this data.