Archive for The Ashes

The England Cricket Team – Another Apology

Posted in Cricket with tags , , , on September 8, 2019 by telescoper

I’m sure that I wasn’t the only person who reacted to England being bowled out for a paltry 67 in the first innings of the Third Ashes Test at Headingley by concluding that the England batsmen were hopelessly inept, that they would certainly lose the match, that the team had absolutely no chance of regaining the Ashes, and that Joe Root should be sacked as England captain.

But after their subsequent one-wicket victory in that match inspired by Ben Stokes, I thought I was wrong, and apologised unreservedly to Joe Root and the England team for having doubted their ability.

Now, after being comprehensively outplayed at Old Trafford, losing by 185 runs, and allowing Australia to retain the Ashes I realise that my previous apology was incorrect, that England’s cricketers are actually inept, and that Joe Root should indeed be sacked as England captain.

I hope this clarifies the situation.

Boris Johnson is 55.

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The England Cricket Team – An Apology

Posted in Cricket with tags , , on August 25, 2019 by telescoper

I’m sure that I’m not the only person who reacted to England being bowled out for a paltry 67 in the first innings of the Third Ashes Test at Headingley by concluding that the England batsmen were hopelessly inept, that they would certainly lose the match, that the team had absolutely no chance of regaining the Ashes, and that Joe Root should be sacked as England captain.

However, after today’s exciting one-wicket victory inspired by Ben Stokes, I now realise that I was wrong, and that the England first innings was a cunning ploy to lure the Australians into a false sense of security before seizing control in the second innings.

I apologise unreservedly to Joe Root and the England team for having so obviously misunderstood their tactics.

I hope this clarifies the situation.

Geoffrey Boycott is 78 (not out).

Test Odds

Posted in Cricket with tags , , on August 24, 2009 by telescoper

I’m very grateful to Daniel Mortlock for sending me this fascinating plot. It comes from the cricket pages of The Times Online and it shows how the probability of the various possible outcomes of the Final Ashes Test at the Oval evolved with time according to their “Hawk-Eye Analysis”.

pastedGraphic

 I think I should mention that Daniel is an Australian supporter, so this graph must make painful viewing for him! Anyway, it’s a fascinating plot, which I read as an application of Bayesian probability.

At the beginning of the match, a prior probability is assigned to each of the three possible outcomes: England win (blue); Australia win (yellow); and Draw (grey). It looks like these are roughly in the ratio 1:2:2. No details are given as to how these were arrived at, but it must have taken into account the fact that Australia thrashed England in the previous match at Headingley. Information from previous Tests at the Oval was presumably also included.I don’t know if the fact that England won the toss and decided to bat first altered the prior odds significantly, but it should have.

Anyway, what happens next depends on how sophisticated a model is used to determine the subsequent evolution of the  probabilities. In good Bayesian fashion, information is incorporate in a likelihood function determined by the model and this is used to update the  prior  to produce a posterior probability. This is passed on as a prior for  the next time step. And so it goes on until the end of the match where, regardless of what prior is chosen, the data force the model to the correct conclusion.

The red dots show the fall of wickets, but the odds fluctuate continually in accord with variables such as scoring rate, number of wickets,  and, presumably, the weather. Some form of difference equation is clearly being used, but we don’t know the details.

England got off to a pretty good start, so their probability to win started to creep up, but not by all that much, presumably because the model didn’t think their first-innings total of 332 was enough against a good batting side like Australia. However, the odds of a draw fell more significantly as a result of fairly quick scoring and the lack of any rain delays.

When the Australians batted they were going well at the start so England’s probability to win started to fall and theirs to rise. But when they started to lose quick wickets (largely to Stuart Broad), the blue and yellow trajectories swap over and England became favourites by a large margin. Despite a wobble when they lost 3 early wickets and some jitters when Australia’s batsmen put healthy partnerships together, England remained the more probable to win from that point to the end.

Although it all basically makes some sense, there are some curiosities.  Daniel Mortlock asked, for example, whether Australia were  really as likely to win at about 200 for 2 on the fourth day as  England were when Australia were 70 without loss in the first innings?  That’s what the graph seems to say. His reading of this is that too much stock is placed in the difficulty of   breaking a big (100+ runs) parnership, as the curves seem to   “accelerate” when the batsmen seem to be doing well.

I wonder how new information is included in general terms. Australia’s poor first innings batting (160 all out) in any case only reduced their win probability to about the level that England started at. How was their batting in the first innings balanced against their performance in the last match?

I’d love to know more about the algorithm used in this analysis, but I suspect it is copyright. There may be a good reason for not disclosing it. I have noticed in recent years that bookmakers have been setting extremely parsimonious odds for cricket outcomes. Gone are the days (Headingley 1981) when bookmakers offered 500-1 against England to beat Australia, which they then proceeded to do. In those days the bookmakers relied on expert advisors to fix their odds. I believe it was the late Godfrey Evans who persuaded them to offer 500-1. I’m not sure if they ever asked him again!

The system on which Hawkeye is based is much more conservative. Even on the last day of the test, odds against an Australian victory remained around 4-1 until they were down to their last few wickets. Notice also that the odds on a draw were never as long against as they should have been either, when that outcome was clearly virtually impossible. On the morning of the final day I could only find 10-1 against the draw which I think is remarkably ungenerous. However, even with an England victory a near certainty you could still find odds like 1-4. It seems like the system doesn’t like to produce extremely long or extremely short odds.

Perhaps the bookies are now using analyses like this to set their odds, which explains why betting on cricket isn’t as much fun as it used to be. On the other hand, if the system is predisposed against very short odds then maybe that’s the kind of bet to make in order to win. Things like this may be why the algorithm behind Hawkeye isn’t published…