Re: Review system: what's the point?

On Dec 9, 8:26 am, "Andrew Dunford" <adunf...@xxxxxxxxxxx> wrote:
"eusebius" <eusebiu...@xxxxxxxxx> wrote in message

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On Dec 9, 2:59 am, Nirvanam <viz.sha...@xxxxxxxxx> wrote:
On Dec 8, 8:34 am, "Andrew Dunford" <adunf...@xxxxxxxxxxx> wrote:

"Nirvanam" <viz.sha...@xxxxxxxxx> wrote in message

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I haven't seen the incident myself, but I'd think that the review
system is designed to operate with a null hypothesis that "on field
umpire's decision is correct". Now, the only way the TV umpire can
reject the null hypothesis is if there is enough conclusive evidence
that the on-field umpire's decision was wrong. The key words here are
'enough' and conclusive. Conclusive can be interpreted as at least
95%
people would agree with the conclusion...in this case "bat touching
ball". If it is conclusive, then the next step is whether that
particular angle is enough to reject/fail to reject the null
hypothesis. In this case there would probably be only 1 meaningful
angle whereas in a run out or grounded catches, we would need 2 to 3
angles concluding consistently. Also the algorithm for decision
making
would follow the sequence of first determining conclusiveness of
evidence, and then determining enough-ness of evidence.

In other words, conclusion = necessary, enough = sufficient. First
ask
if it the necessary thing is ticked, then ask if the sufficiency has
been ticked.. Then you have enough ground to reject the null
hypothesis / over-turn on-field umpire's decision

So, did Rauf have "conclusive" evidence = no. Since the "necessary"
aspect itself is not ticked, there is no point in going to the
sufficiency aspect at all. The null hypothesis stays. Therefore,
Rauf's decision would be a wrong one.

The claim one can make is that Rauf thought it was conclusive. The
important thing is to separate subjective opinion from objective
data.
What Rauf "thought" is immaterial now because the decision has been
made. The question to be asked is: Would 95% of the people who saw
the
same thing also "think" that the same evidence as "conclusive". As,
logical/rational methods and systems stand today, if it is less than
95% it makes no sense to reject the null hypothesis. (No need to get
pedantic about taking the alpha-risk and reducing it to less than
95%)

So, was the evidence so conclusive that 95% people would've thought
the same way as Rauf did?

Don't know why you think that a certain percentage of people agreeing
has
any relevance - umpiring decisions are not made by polling the general
public, who in any case are not trained to interpret what they see in
the
way that an umpire is. The only thing the third umpire need concern
himself
with is what 'evidence' he personally believes exists.

Andrew

The point is not about certain percentage of people agreeing, it is
about 95% of the times a particular event happens. The people thing
comes in only because this particular case relies on people making the
call. In hypothesis testing what we normally do is to see whether a
particular thing when done 100 times, is there any evidence to suggest
that 95 of those 100 times the event will happen in a particular way.
For ex - suppose you feed some inputs to a financial model and it
throws up an estimate. You then see the actual, let's say the actual
and the estimate given by the model are within an acceptable range.
Now suppose you gave inputs to the financial model 100 different
times, then you see the difference between actual and estimate for
each instance. If this difference is acceptable 95% of the time then
the model is good enough, that'll be the conclusion.

Similarly, in the umpire case, we are asking if 100 different people/
umpires see this video, will 95 of them conclusively say it is "out"?
Or put in a different way: is the evidence so conclusive that 95 out
of 100 people would also infer, like you/Rauf/whoever, that the ball
touched the bat? If they won't then there is no point in changing the
status quo, in this case on-field umpire's decision. You may decide
what that level should be based on the criticality of the item. For
ex, if you are testing a CT scanner or some medical device, you would
probably want all 100 instances to give you correct output. If the
thing you are testing is the process of ball manufacturing. You might
be OK if 90 balls out of a sample of 100 balls have their diameter
within an acceptable range. If you are testing the manufacturing
process of candy bars. You might be OK with even just 50 of them
having a length difference which is less than 1mm of the standard
size, maybe 90% for length difference of less than 1 cm of standard
size. That is the "risk" you take in rejecting the status quo. The
risk you are taking in our umpire's case is 5% in other words there
would not be more than 5% of the people/umpires who were asked to make
a decision with the same evidence who will then decide that it was not
out. Clearly the evidence wasn't that good that you won't find even 5%
people disagreeing (or 95% agreeing). Hence there is not enough data/
evidence to suggest that the status-quo should be changed.

Generally, most tests set 95% as a thumb rule (but depending on
criticality of the thing u are testing you may want to reduce it or
increase it).- Hide quoted text -

- Show quoted text -

Whatever, but the point remains that Rauf's overrule was indeed
correct. There was substantial deviation, there was a substantial
noise. You could say, that this was as out to the naked eye as the
famous Symonds decision, which led to such admirable restraint from
nationalistic cricket fans, players and public.

The problem was, 'hotspot' is not set up to pick anything up that
cannot be seen from a frontal view from the bowler's end umpire's
perspective. If someone had've thought of the possibility of such a
situation and set it up so it could see a side on view, then there
would have been little or no dispute.

It is easier also to pass judgement on such cases after seeing them
onesself, extensive viewing in fact is advantageous.

As there appears to be no definition of what constitutes 'conclusive
evidence' that the ball hit the bat in the case of an edged catch, we're not
in a very strong position to determine the correctness or otherwise of
Rauf's decision, in which case he is justified in overruling on what *he*
saw.

Andrew

Let common sense be your guide. To me, the bat connecting with the
ball is a good enough definition. What other definition of conclusive
evidence do we have?
We saw the ball change direction after passing the bat, and a notable
deviation. That is a snick, every good umpire instinctively knows
this. You don't need it codified.
What would improve things would be if hotspot was modified in the way
I suggested.

That is, if hotspot is foolproof. What if a massive dungbeetle
collided with the edge of Chanderpaul's bat in mid flight?
.

Relevant Pages

  • Re: Review system: whats the point?
    ... the only way the TV umpire can ... angles concluding consistently. ... evidence, and then determining enough-ness of evidence. ... said it was out conjectured based on the fact that the ball deviated ...
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  • Re: Review system: whats the point?
    ... the only way the TV umpire can ... >> angles concluding consistently. ... >> evidence, and then determining enough-ness of evidence. ... of 100 people would also infer, like you/Rauf/whoever, that the ball ...
    (rec.sport.cricket)
  • Re: Review system: whats the point?
    ... the only way the TV umpire can ... angles concluding consistently. ... evidence, and then determining enough-ness of evidence. ... The claim one can make is that Rauf thought it was conclusive. ...
    (rec.sport.cricket)
  • Re: Review system: whats the point?
    ... the only way the TV umpire can ... angles concluding consistently. ... evidence, and then determining enough-ness of evidence. ... of 100 people would also infer, like you/Rauf/whoever, that the ball ...
    (rec.sport.cricket)
  • Re: Review system: whats the point?
    ... >>> reject the null hypothesis is if there is enough conclusive evidence ... >>> angles concluding consistently. ... The only thing the third umpire need concern ... back to the on-field umpire what he sees"...did Asad Rauf actually see ...
    (rec.sport.cricket)