[quote]
On 2003-06-18 11:48, jfc wrote:
Now, I have only one issue with osulldj and La Mer and perhaps the rest of humankind, namely:

Typically it's wrong to make time comparisons from different meetings. And that's what averaging is, in a roundabout way. So averaging times is wrong.
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La Mer: I agree in principle with what you've written, in particular taking a speed rating from one meeting and comparing it with a speed rating taken at another meeting.

But that is not what is being discussed and IMO if you have sufficient data then by trimming the extremes then some conclusions can be drawn from what is left, i.e. the number of maiden races used in my example was 163 (excluding 21 2yo maidens which tend to run slower times) less ten percent at either end, so my standard times were based on 130 races, which ranged from 70.45s to 72.25s, a spread of 1.80s. Had all 163 races been used, then they would have ranged from 69.57s to 74.59s, a spread of 5.02s.

Over 1200m then a spread of that nature immediately indicates that something in not quite right - either the slower times were run on tracks other than good (the most probable cause), or the timing device was incorrect, or the race was run over a longer distance than 1200m.

Whatever, it really does not matter so long as such occurences are taken out of the equation - trimming does this - in fact I eliminated the 74.59s prior to the trimming, as the next slowest time was some 1.50 seconds faster.

Having done that, then I am reasonably confident that a useable standard time has been obtained - remembering of course that this is not an exact science for reasons already mentioned.
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JFC: Official track readings are notoriously untrustworthy so there could be even 1 second's difference between two allegedly good tracks. Penetrometers also appear fishy, perhaps because those readings are performed many hours before the races start.

Therefore I only make comparisons between races at the same meeting.

So in the earlier Kembla example, there were 43 Opens and 167 Maidens available, but I was only prepared to compare the 29 matches on identical days.
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La Mer: Agree totally re your track conditions/penetrometer comments.

However, I admit to being a little confused by your comments "comparisions between races at the same meeting".

Are you referring to 'same' day or 'identical' days, i.e. occurences where you consider the days to be identical, and if not then how can you have 29 'same' day occurences, unless of course you are referring to horses and not races?
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JFC: It's also fascinating that he finds that the superior Class 2's have inferior times to Class 1's. Confirming my earlier claim.
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La Mer: I've also found some blurring of the times further up the class ladder with race types like Rs1mw, Rs2mw, and I expect the replacement races classes SC1mw and SC0mw races will show similar blurring - Open Handicaps and Listed races are similar as well.

As mentioned, this has been a good disussion and my appreciation to both osulldj and JFC for participating - I trust that those that asked the original questions are getting something out of all of this.