3rd Ashes test Old Trafford

mystiroakey wrote:They are based on a fairytale vision of the days of old..

Mike Selig wrote:Mysti you place too much faith in technology.

I don't claim to be an expert (my technical expertise lies in mathematics, which plays a part in Hawk-eye I'm sure, but I can't claim to understand how) but I have spoken to guys who are.

Hawk-eye is a brilliant piece of technology, but it is not perfect. It doesn't tell you definitively where the ball is going to end up, all it does is make a projection based on all the information it has available. The further away you are from the stumps, the more uncertain this projection is, and this is an exponential rather than a polynomial equation (which in layman's terms means the uncertainty increases dramatically rather than gradually).

Currently in order to make it understandable to the layman, the ICC have, mistakenly in my view, stuck to the same 50% criteria regardless of how far out the impact is. In fact, to use the technology optimally this should change depending on where the impact is, how much swing/spin there was prior to the impact etc. The guys who made and implement Hawk-eye know this, but to maintain a degree of clarity, the ICC has stuck to the same criteria for all decisions.

Because once you get far enough away from the stumps with the impact, even the 50% rule becomes too aleatory, the ICC have further introduced a distance from the stumps beyond which any not out decision can be maintained regardless. Again this is an oversimplification of the problem, as a ball hitting the base of middle is still undoubtedly hitting the stumps, but it was done for the sake of clarity. Before the 2011 WC, the distance at which the level of uncertainty became too high was 2.5 m from the stumps, now because Hawk-eye have improved their system (according to themselves, but according to a couple of guys I've spoken to it is plausible) it is 3m.

But that does not mean that a ball which strikes the batsman 2.8 metres out carries the same degree of uncertainty as the one which strikes him half a metre out (e.g. Smith to Swann on day 1) - far from it. the reason the distance is 3m is because on tests conducted in laboratory conditions (which is obviously very different from real conditions) that was close enough to the distance which came up. But laboratory conditions don't take into account things like various bounce, and crucially in England where the ball can swing after it passes the bat.

In an ideal world the degree of uncertainty should reflect the actual degree, and Hawk-eye themselves admit that beyond 2.5 metres they are only really certain if a good part of the ball is predicted to hit middle.

Similarly Hawk-eye has different degrees of certainty depending on how close the ball pitches to the pad - the close the bounce the more uncertain the prediction, because the amount of spin/movement is unclear.

KP was out to Watson, according to Hawk-eye, but Hawk-eye can get these things wrong, and in this case was less certain of that fact than it was for the Smith vs Swann decision for example, because of the degrees of certainty relative to the distance. In my view, there was too much unpredictability involved, particularly with the ball swinging (and so could have swung further down the leg-side). For that reason, those kind of decisions are not the kind I wish to see given out. A human can't be sure, but neither can Hawk-eye.

mystiroakey wrote:"without resorting to petty one-liners and insults"

again you have taken offence when there is none to be taken- Where is the insult?- where is the one liner?

Every time I debate and argue your points you come back with this nonsense!!

guildfordbat wrote:

Mike Selig wrote:Mysti you place too much faith in technology.

I don't claim to be an expert (my technical expertise lies in mathematics, which plays a part in Hawk-eye I'm sure, but I can't claim to understand how) but I have spoken to guys who are.

Hawk-eye is a brilliant piece of technology, but it is not perfect. It doesn't tell you definitively where the ball is going to end up, all it does is make a projection based on all the information it has available. The further away you are from the stumps, the more uncertain this projection is, and this is an exponential rather than a polynomial equation (which in layman's terms means the uncertainty increases dramatically rather than gradually).

Currently in order to make it understandable to the layman, the ICC have, mistakenly in my view, stuck to the same 50% criteria regardless of how far out the impact is. In fact, to use the technology optimally this should change depending on where the impact is, how much swing/spin there was prior to the impact etc. The guys who made and implement Hawk-eye know this, but to maintain a degree of clarity, the ICC has stuck to the same criteria for all decisions.

Because once you get far enough away from the stumps with the impact, even the 50% rule becomes too aleatory, the ICC have further introduced a distance from the stumps beyond which any not out decision can be maintained regardless. Again this is an oversimplification of the problem, as a ball hitting the base of middle is still undoubtedly hitting the stumps, but it was done for the sake of clarity. Before the 2011 WC, the distance at which the level of uncertainty became too high was 2.5 m from the stumps, now because Hawk-eye have improved their system (according to themselves, but according to a couple of guys I've spoken to it is plausible) it is 3m.

But that does not mean that a ball which strikes the batsman 2.8 metres out carries the same degree of uncertainty as the one which strikes him half a metre out (e.g. Smith to Swann on day 1) - far from it. the reason the distance is 3m is because on tests conducted in laboratory conditions (which is obviously very different from real conditions) that was close enough to the distance which came up. But laboratory conditions don't take into account things like various bounce, and crucially in England where the ball can swing after it passes the bat.

In an ideal world the degree of uncertainty should reflect the actual degree, and Hawk-eye themselves admit that beyond 2.5 metres they are only really certain if a good part of the ball is predicted to hit middle.

Similarly Hawk-eye has different degrees of certainty depending on how close the ball pitches to the pad - the close the bounce the more uncertain the prediction, because the amount of spin/movement is unclear.

KP was out to Watson, according to Hawk-eye, but Hawk-eye can get these things wrong, and in this case was less certain of that fact than it was for the Smith vs Swann decision for example, because of the degrees of certainty relative to the distance. In my view, there was too much unpredictability involved, particularly with the ball swinging (and so could have swung further down the leg-side). For that reason, those kind of decisions are not the kind I wish to see given out. A human can't be sure, but neither can Hawk-eye.

Mike - that is a very informative and helpful post, thanks.

My wife is a mathematics graduate and has a certain appreciation of cricket (certainly more than some on here) but just cannot get the concept of ''umpire's call''. As you can probably tell, the fun never stops at Guildford Towers!   Anyway, I'll see if I can educate her further with your excellent post.

Do you happen to know how far down the track a batsman needs to be to be automatically deemed ''not out''? That is a factor which could well have inflenced Clarke's thinking on not reviewing the Pietersen lbw appeal. As I now understand it, Pietersen wasn't that sufficiently far down but Clarke would probably have been unsure - another factor to tip the scales against a review. As I said to Alfie, I just thought in the situation it was worth a punt by Clarke but, unlike some of the media, make no criticism of him for not doing so.

You probably don't much like my expression ''take a punt'' in deciding when to use DRS. I don't either. However, that unfortunately does seem how it is to be applied currently.

GSC wrote:Forecast really doesn't look good. Australia probably have to get the follow on

dyrewolfe wrote:Wow - runs flowing for England at the moment.

Some interesting comments about Cook declaring just short of the follow-on saving target, so we have to bat again and set Australia a target, rather than the other way round.

Clever or utterly stupid?

trebellbobaggins wrote:

dyrewolfe wrote:Wow - runs flowing for England at the moment.

Some interesting comments about Cook declaring just short of the follow-on saving target, so we have to bat again and set Australia a target, rather than the other way round.

Clever or utterly stupid?

 Crazy.

ChequeredJersey wrote:The further into this match we go the more it looks like Clarke's declaration let us firmly off the ropes

Duty281 wrote:2 consecutive fours and England have avoided the follow-on. Cracking positive approach this morning!

Duty281 wrote:http://uk.weather.com/weather/hourByHour-UKXX0092:1:UK

Dare I be optimistic about the weather? That forecast looks rather good.

GSC wrote:If it reaches the point where hawk eye is just too inaccurate, then it cannot be used to overturn a decision

mystiroakey wrote:Well done england- Now to get on to 400 plus