tag:blogger.com,1999:blog-6059983310325678283.post4783764588845687232..comments2022-07-22T03:23:53.692+01:00Comments on The Power of Goals.: Poisson, Predictions and a Tense Last Ten Minutes.Mark Taylorhttp://www.blogger.com/profile/15514407542599931686noreply@blogger.comBlogger23125tag:blogger.com,1999:blog-6059983310325678283.post-5439022992567323272015-10-07T10:16:08.178+01:002015-10-07T10:16:08.178+01:00Many thanks for i nice articleMany thanks for i nice articleAnonymoushttps://www.blogger.com/profile/02267319880860869705noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-64718969992057407352015-02-24T00:56:17.592+00:002015-02-24T00:56:17.592+00:00Hi there, Mark!
What a beautiful job you did here...Hi there, Mark!<br /><br />What a beautiful job you did here, mate. Congratulations! I'm not sure if I'll be replied once this article was wrote in few years ago, but lets try.<br /><br />I would like to know why the equation with ^0.84, I know that's because it fits well. But where did you get it? Did you invented it? Or is there any other article that explain this equation?<br /><br />And the most important to me is: when you crossed your prediction with Betfair it fitted fine. But are you sure Betfair just uses the average scored goals in a poisson model? What did you do to this fit so very well, my friend?<br /><br />I hope that I was clear enough, Mark.<br /><br />And again, congratulations for your post. =)<br /><br />Best RegardsDavidnoreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-85748364065617705752014-06-24T20:32:08.951+01:002014-06-24T20:32:08.951+01:00Hi Mark
That's a really great article and ver...Hi Mark<br /><br />That's a really great article and very informative thank you.<br /><br />Could I ask a quick question please, if you don't mind.<br /><br />I understand the whole principle of the poisson calculations for pre match and then as you mentioned using your calculation of (^0.84) to get an in-running calculation for the remaining goal expectancy, however what I don't understand is when one team goes 1-0 up, how do you then calculate the goal rates? (for example on your Stoke/WHU game from the 33rd minute onwards).<br /><br />Thanks <br /><br />Andy<br /><br />Andynoreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-16637651117408994262014-04-30T18:42:53.910+01:002014-04-30T18:42:53.910+01:00Hi Rory,
it gives the best fit for describing real...Hi Rory,<br />it gives the best fit for describing real life data over the long term.Mark Taylorhttps://www.blogger.com/profile/15514407542599931686noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-63168352448719151982014-04-30T18:19:21.528+01:002014-04-30T18:19:21.528+01:00Where did you get 0.84 from?Where did you get 0.84 from?Anonymoushttps://www.blogger.com/profile/13877600766733703389noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-7496326860620239752013-05-06T13:27:37.219+01:002013-05-06T13:27:37.219+01:00Hi Mark, See www dot sortmyfootball dot com, you c...Hi Mark, See www dot sortmyfootball dot com, you can see the goal expectations for each team including recent moves. I suspect you may find this resource useful. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-69387524622910957622012-12-17T18:25:14.806+00:002012-12-17T18:25:14.806+00:00ok, thank you, now i see :-)ok, thank you, now i see :-)Anonymoushttps://www.blogger.com/profile/18359730881843044763noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-66578853853522102402012-12-17T17:33:28.534+00:002012-12-17T17:33:28.534+00:00Hi Knud,
let's say you've got half the mat...Hi Knud,<br />let's say you've got half the match remaining and team A had an initial goal expectancy of exactly 2 goals. The proportion of the match remaining is 0.5. <br /><br />Proportion of time remaining raised to the power of 0.84 = 0.5^0.84= 0.559.<br /><br />0.559 * 2(the initial goal expectancy) = 1.12 = goal expectancy for the remainder of the match.<br /><br />1.12 goals is 56% of the original goal expectancy of 2 goals. This helps to account for the gradual increase in scoring, on average as matches progress.<br /><br />An original goal expectancy of 1.5 has decayed to around 0.838 goals with half the match remaining. Again around 56% of the original figure.<br /><br />Mark.Mark Taylorhttps://www.blogger.com/profile/15514407542599931686noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-54560003500531226002012-12-17T15:29:12.338+00:002012-12-17T15:29:12.338+00:00I am not sure that i understand. Can you give an e...I am not sure that i understand. Can you give an example of how you calculate that when the teams expected score is 2,0 and 1,5 for instance please?Anonymoushttps://www.blogger.com/profile/18359730881843044763noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-75584103963776572222012-12-17T08:39:14.365+00:002012-12-17T08:39:14.365+00:00Hi Knud, depending on how you treat added time whe...Hi Knud, depending on how you treat added time when team expectation is 2 the expectation for the second half works out at around 1.13, just over 56%.<br /><br />MarkMark Taylorhttps://www.blogger.com/profile/15514407542599931686noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-643008827585420122012-12-14T06:28:56.227+00:002012-12-14T06:28:56.227+00:00Ok, but it only fits when the expected team score ...Ok, but it only fits when the expected team score is set to 1,0. when the teams expectation score is 2,0 the outcome for 2. half would be 1,0 which is only 50% and not 56%.Anonymoushttps://www.blogger.com/profile/18359730881843044763noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-73349007870360268862012-12-12T15:58:17.371+00:002012-12-12T15:58:17.371+00:00Hi Knud,
it gives the best fit to how the actual s...Hi Knud,<br />it gives the best fit to how the actual scoring rate changes over time. <br /><br />markMark Taylorhttps://www.blogger.com/profile/15514407542599931686noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-5440775231779692632012-12-12T11:59:39.661+00:002012-12-12T11:59:39.661+00:00Why is it that you do the ^0.84 ?Why is it that you do the ^0.84 ?Anonymoushttps://www.blogger.com/profile/18359730881843044763noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-59769611181317999312012-12-01T10:42:38.975+00:002012-12-01T10:42:38.975+00:00Rich,
I don't "love" anything I'...Rich, <br />I don't "love" anything I've posted.<br /><br />Feel free to outline the failings of this approach, host it and I'll gladly add the link here, but a continuous procession of strawmen is hardly helpful.<br /><br />thanks for your comments, <br />mark. Mark Taylorhttps://www.blogger.com/profile/15514407542599931686noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-50631113363248676542012-11-30T22:45:14.664+00:002012-11-30T22:45:14.664+00:00An outcome is not what's been identified - onl...An outcome is not what's been identified - only a variation in the predicted price. The hoped for outcome may not come to fruition. You love it, I don't. Nuff said.RichPhttps://www.blogger.com/profile/10557785282124380251noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-42567249913712530962012-11-30T10:20:58.034+00:002012-11-30T10:20:58.034+00:00"if you followed Poisson predictions for the ..."if you followed Poisson predictions for the Man Utd game you would probably be going for 3-1 at the start and after the goal" <br /><br />Why would you ? I've never suggested you pick the most likely outcome, assuming your point is that 3-1 is the most likely correct score outcome, (I'd disagree, btw). You're measuring your opinion against the opinion of others, one model against another.<br /><br />"As far as I can see all Poisson does is tell you when the price is slightly wrong, which will give you the opportunity to make a value bet.."<br /><br />So you've identified an outcome that occurs more frequently than implied by the odds in the long term. You'll have to explain the downside of this.<br /><br /><br />Mark Taylorhttps://www.blogger.com/profile/15514407542599931686noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-31179748889385552352012-11-30T09:47:11.116+00:002012-11-30T09:47:11.116+00:00Therein lies the problem - if 6 matches are unreli...Therein lies the problem - if 6 matches are unreliable how can Poisson give you the final score on the single selected match. We don't bet in batches of 30. I'm only guessing, but if you followed Poisson predictions for the Man Utd game you would probably be going for 3-1 at the start and after the goal. Then it would be reducing from that score right up to the final whistle? Well that's obvious and you don't need Poisson for that. As far as I can see all Poisson does is tell you when the price is slightly wrong, which will give you the opportunity to make a value bet, but you'd still have lost your money in those two matches.RichPhttps://www.blogger.com/profile/10557785282124380251noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-50560881686754491232012-11-29T22:28:20.887+00:002012-11-29T22:28:20.887+00:00Goals based Poisson predictions tally extremely we...Goals based Poisson predictions tally extremely well with long term reality, both pregame and in running. <br /><br />"The expectations then would not have got anywhere close to the final score of 7-4." Why would they? The goal expectations alone don't predict a score, just the average number of goals those specific teams would score or concede in a large number of repetitions. The Poisson then gives an estimation of the individual scores. I'd imagine a 7-4 would turn up around once every 120,000 games.<br /><br /><br />What teams have done in their last 6 or 8 games gives you very little indication of what they will do in their next match whatever you do with the numbers. I suggest a minimum of 30 matches, suitably smoothed are used to calculate goal expectations.<br /><br />The relative abilities of the teams is one of the easiest factors to deal with, blisters probably less so, although their influence on match outcome is probably overrated. The biggest extraneous influences are current score. Trailing teams become slightly more likely to score than previously, leading teams slightly less so. Again relatively easy to incorporate, although how to improve a raw Poisson wasn't ever part of this post. <br /><br />"Seconds after the goal a ManU win was traded at 1.09 but this drifted to 1.12 or 1.13 and stayed there right into injury time. Did Poisson predict this?" <br />Within a few % points, yes. It tracked United's price as the game unfolded and could, if needed have produced an estimation of the chances that United would lead after the first minute, which may have been superior to an alternative opinion. <br /><br />Models, even ones full of bunkum try to attach a likelihood to a particular outcome, they don't say this game will finish 7-4. Life would be very boring if they did.<br /><br />thanks for your comments.Mark Taylorhttps://www.blogger.com/profile/15514407542599931686noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-38617605487987748892012-11-29T19:23:57.253+00:002012-11-29T19:23:57.253+00:00Of course if you delve a little deeper it becomes ...Of course if you delve a little deeper it becomes obvious that this is pure bunkum. A team's goal expectancy is seriously dependent on the availability and mindset of each and every player utilised,together with the availabilty and mindset of the each member of the opposition and how they all interact with or against each other. Then extraneous influences such as pre-match fatigue, transfer requests, subconscious bias of the officials, over-use or under-use of cautions, timing of cautions, pitch conditions, adverse weather, precariousness of the manager's tenure, blisters, distracted/pre-occupied officials and so on, and so on. When you add in the relative ability of players facing each other it becomes obvious that there are too many imponderables to accurately predict anything. When Portsmouth entertained Reading in 2007, they had scored 1 or less goals in 5 of the preceding 6 games, while Reading had scored a grand total of 5 goals in 8 games. The expectations then would not have got anywhere close to the final score of 7-4. The sensible route is to treat aggregated analysis as an aid to serious analysis, not THE analysis. Have a look at the live-odds in the last few minutes of a match. They appear to go the wrong way, then stall until the last few seconds of the match. The reason for this is that it only takes a moment to score a goal. Players are human and humans are unpredictable, unlike Poisson analysis. How many people had Man Utd v West Ham down for 1-0? Seconds after the goal a ManU win was traded at 1.09 but this drifted to 1.12 or 1.13 and stayed there right into injury time. Did Poisson predict this? I doubt it. Poisson predicts/instructs prices, but it doesn't predict outcomes.RichPnoreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-16361153170365855572012-11-22T09:10:25.909+00:002012-11-22T09:10:25.909+00:00That's a fair assumption. Large sample analysi...That's a fair assumption. Large sample analysis of the Betfair in running soccer prices does indicate that they do a very good job of efficiently tracking real life outcomes. This suggests that you can produce a decent model with just a few inputs (goals, time elapsed and red cards)because a suitably tweaked Poisson mimics betfair....although as you suggest betfair prices may largely equal a poisson approach. Mark Taylorhttps://www.blogger.com/profile/15514407542599931686noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-62940520211209693952012-11-21T20:43:12.770+00:002012-11-21T20:43:12.770+00:00Interesting stuff, do you not think one of the rea...Interesting stuff, do you not think one of the reason that poisson and betfair prices are so similar is mainly due to the fact the market markers on Betfair are simply using poisson within the majority of bots operating? Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-53733464921814757982012-11-21T19:01:31.440+00:002012-11-21T19:01:31.440+00:00I got the lite data in the middle of August and th...I got the lite data in the middle of August and the play by play for Bolton Man City a week or so later. So pretty quickly after registering.<br /><br />Have you tried asking at the opta pro micro site<br /><br />http://www.optasportspro.com/en/about/optapro-blog/posts/2012/blog-optapro-an-online-hub-for-the-analytical-community.aspx<br /><br />It's been set up to discuss and share the project. Mark Taylorhttps://www.blogger.com/profile/15514407542599931686noreply@blogger.comtag:blogger.com,1999:blog-6059983310325678283.post-68895241826058047612012-11-21T18:31:49.037+00:002012-11-21T18:31:49.037+00:00Excuse me for being completely unrelated to this, ...Excuse me for being completely unrelated to this, but how long did it take you for mcfc analytics to send you the opta data set? I registered nearly a week ago and haven't heard anything.Anonymousnoreply@blogger.com