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Why fillies and mares don’t need a weight allowance at the highest level


Chief Stipe

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Why fillies and mares don’t need a weight allowance at the highest level

James Willoughby  |  MAY 18, 2017  |  
1 Comment
 

2013%20Arc%20-%20Treve.jpg__760x480_q85_ Treve winning the Arc in 2013: the three-pound weight allowance she received looks fairly irrelevant in this case

Fillies and mares receive a weight allowance when taking on male horses around the world. This is supposed to equalise opportunity and make the best races open to either sex more competitive. Does it do the supposed job? Should we even consider removing it for the best races, so as to reward the best athlete, rather than merely rewarding the best runner considering its sex? Let's see what the statistics say.

Table 1 contains the record of female horses in Group and Graded races across the world since January 1, 2011, when facing at least one male opponent, including geldings and ridglings:

Table  1: female horses in 5 years of Group/Graded races

Country

W (wins)

R (runs)

SR

IV

Australia

284

2894

10

1.13

New Zealand

105

1400

8

0.95

Japan

71

1125

6

0.97

France

82

861

10

0.84

Britain

53

554

10

0.95

Ireland

43

336

13

0.89

Argentina

32

270

12

1.31

Germany

23

262

9

0.76

Chile

12

182

7

0.79

Brazil

12

142

8

0.78

Italy

15

126

12

1.07

South Africa

15

124

12

1.59

USA

17

121

14

1.27

Peru

12

105

11

1.06

UAE

12

95

13

1.51

Canada

5

34

15

1.29

Hong Kong

0

32

0

0

Sweden

0

12

0

0

Turkey

1

8

12

1.01

Singapore

0

7

0

0

Norway

1

7

14

1.47

Qatar

1

3

33

3.67

Denmark

1

3

33

4.00

Saudi Arabia

0

2

0

0

Let’s take a walk through the columns. ‘W’ is total winning horses; ‘R’ is total runners; ‘SR’ is Strike Rate (winners per 100 horses), and ‘IV’ is Impact Value (ratio of actual Strike Rate to expected Strike Rate considering size of the field).

Two statistics are worthy of note: R – the number of runners – varies tremendously across the world. Relative to the number of Group and Graded races staged, it is relatively common to see the sexes in competition in Australia and, particularly, in New Zealand. But in the USA, the belief that females are hugely disfavoured on dirt, plus the number of races restricted to females, makes it rare to see the sexes in competition.

IV – Impact Value – is a simple but useful metric in many situations. It measures the rate of winners for a category considering the proportion of runners representing that category. An IV of 1.00 is a win rate no more or less than the average in the size of fields encountered; for instance, a 10 percent strike rate in 10-runner fields. IV less than 1.00 is underperformance and IV greater than 1.00 overperformance; IV 2.00, for instance, represents a strike rate twice as high as random chance.

 
trc_strip1.gif

In this setting, IV greater than 1.00 for females implies an IV less than 1.00 for males, for it should be obvious that sex is a binary value. So, you can quickly see how females have done in each country; it seems as if the general belief that females find it hard to beat males in the US is unjustified from these numbers.

That last statement must be tempered, however, by an important caveat when dealing with statistics that are the result of observation and not experimentation. In the first case, samples of statistics are very likely to be biased. This means that females are not selected at random to take on males, but often because their connections believe they have a good chance of winning, or else why not just stick to their own sex?

Proceeding with caution, then, let us lump all the statistics in Table 1 together, to examine how females fare around the world in the aggregate. Consider Table 2a and 2b.

Table 2a: Category of sex and record, mixed Group/Graded races 2011-

Category

W (wins)

R (runs)

SR

IV

Colt

1074

9054

12

1.17

Horse

3447

31034

11

1.11

Filly

165

1648

10

1.08

Mare

632

7057

9

0.99

Ridgling

44

412

11

0.90

Gelding

2135

25550

8

0.85

Table 2b: Binary-valued sex and record, mixed Group/Graded races 2011-

Sex

W (wins)

R (runs)

SR

IV

Male

6700

66050

10

1.00

Female

797

8705

9

1.00

Tables 2a and 2b provide great support for the various schema of sex allowances (3lb to 5lb) around the world. Entire male horses have the highest IV, geldings and ridglings have the lowest IV and female horses are in the middle, with fillies (4yo and younger) doing better than mares (5yo+). All of this is no revelation.

When we combine the different categories of sex which are conditioned for in Table 2a, a nice result is forthcoming, expressed in Table 2b. Remembering we are dealing only with races contested by both male and female horses, the IV of both is 1.00. In other words, sex allowances around the world seem to do a really good job.

But, as thorough data scientists, we should not stop there. Instead, let’s take a step back and think about why female racehorses receive an allowance at all. Using our Group and Graded race data since January 1, 2011, let’s examine the distribution of the two sexes using Racing Post Ratings (RPR), a widely used benchmark of racing merit.

Figure 3: the distribution of merit 

rpr_by_sex.jpegFigure 3 above shows the distribution of performances in Group races for male and female racehorses across the world, using the RPR scale. The horizontal axis is the scale of RPR and the vertical axis their relative frequency (expressed using the technical measure ‘probability density’). The green area represents the ‘mass’ of male racing talent and is transparent, allowing for the comparison with the pink area of females. That the green graph is shifted to the right is strong evidence that male horses are better than females, as presupposed. At least, on average.

And it is this last word which turns out to be important. The mean of a population (which is the proper terms for the metric we loosely refer to as ‘the average’) is a measure of its central tendency, and if we say that male horses are better than female horses ‘on average’ then this is most likely to be true when we pick an ‘average’ male and compare him with an ‘average’ female.

 
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In the tails of the distribution – and specifically the right tail where horses with high RPR are to be found – it is much less likely that a given male will be better than a given female, because good horses of both sexes are rare. So, if we made every horse with RPR greater than 115 a ping-pong ball and had separate bags of females and males, there is no guarantee the male would be better, if we drew a ball from each bag at random.

Yet, in a race featuring elite performers of both sexes in competitions, females always get a weight allowance, just as if an average female is being pitted against an average male. This is a dangerous assumption and, as we have established, could easily be violated in real-world encounters.

Guess what? The statistical theory holds. Using the evidence of Table 2a and Table 2b, we previously found that males and females do equally well when matched in Group and Graded races. But a different picture emerges when we condition the results by the classification of the Group race, as Table 4 shows:

Table 4: Category of female horses, mixed Group/Graded races 2011-

Grade

W (wins)

R (runs)

SR

IV

1

263

2775

9.5

1.17

2

168

1864

9.0

0.99

3

366

4066

9.0

0.93

Here is an important result! As we make races for better horses, and eventually reach the best on the planet, IV shows that female horses have a better record than males. Again, this is undoubtedly a function of ‘selection bias’ - owners and trainers only ask the best females to take on males – but there is clearly an opportunity there to exploit. And the sample-size of 2775 female runners hardly suggests that much selectivity is involved.

And, finally, in case you needed it confirmed, we are talking turf here, not dirt, as Table 5 confirms:

Table 5: how the surfaces compare

Surface

W (wins)

R (runs)

SR

IV

Turf

760

8281

9

1.02

Dirt

33

382

9

0.88

Tapeta

4

25

16

2.00

Polytrack

0

14

0

0

Leaving the surface aside, however, one wonders at the sagacity of allowing females an allowance. It isn’t difficult to think of dominating victories in the Prix de l’Arc de Triomphe, for instance, as five of the last six winners have been female. This is somewhat misleading, as the brilliant Treve accounts for two of them, but did she need an allowance? Did last year’s winner Found?

As we have established, it isn’t possible to make a definitive case that the female weight allowance should be removed for Group 1 and Grade 1 races, but if you held a prior belief that this should be done for other, objective reasons, the data at least supports your view.

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1 hour ago, Chief Stipe said:

The math in this article might be a bit beyond Thomaas!

It probably is, more importantly though, the interpretation of it. It's beyond others as well obviously including NZTR unfortunately which is why we have a completely stuffed handicapping system.

That said, this is not some sort of arrogant campaign to bamboozle those who have a maths phobia. It's the principals that are important here. While I can write the kind of software queries required to do this sort of analysis, I usually get help because the more competent can do what would take me days in minutes.

Neither Thomaas nor NZTR among others seem able to grasp this when examining the impact of any variable on results. I may try to explain this in simple understandable terms when I have time. For now, I'd just say that the above has been done right and is appropriately tempered with caution that it is not conclusive and can not be without adjustment for the chance/ability of all runners.

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21 hours ago, Chief Stipe said:

The math in this article might be a bit beyond Thomaas!

Says someone who can't read basic race results..and doubles down when it's pointed out..next

btw why are you starting new threads when a topic has already been established?

weird

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19 hours ago, curious said:

It probably is, more importantly though, the interpretation of it. It's beyond others as well obviously including NZTR unfortunately which is why we have a completely stuffed handicapping system.

That said, this is not some sort of arrogant campaign to bamboozle those who have a maths phobia. It's the principals that are important here. While I can write the kind of software queries required to do this sort of analysis, I usually get help because the more competent can do what would take me days in minutes.

Neither Thomaas nor NZTR among others seem able to grasp this when examining the impact of any variable on results. I may try to explain this in simple understandable terms when I have time. For now, I'd just say that the above has been done right and is appropriately tempered with caution that it is not conclusive and can not be without adjustment for the chance/ability of all runners.

Oh my...says someone who can't understand basic "retrospective" Englaise...

All one needs to read in this Racing rant from your 'James' ( obviously you know him) is the last conclusion...

"it isn't possible to make a definitive case" after his 'massive' 5 years...

Yea that...why doesn't he write his own 'Handicapping Shang Gree La' then...

...like you and your Besty did for NZTR...who binned it as unworkable...

It wouldn't have included a wide range by any chance...which would have seen even more of a mass exodus to Aus. with a less severe system that's acceptable to most stakeholders??

Perhaps you'd be so kind to put your ideas up here on what you'd proposed and we'll disect the 'document'

Im hoping it'll include an acknowledgement that the physiological difference between not only immature age horses is there...but the fact females are physiologically smaller on average as well...

Perhaps your 'system' will include the ability to weigh each participant and/or include the exact birth dates instead of a one fits all option?

cant wait...thanks

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3 minutes ago, curious said:

You've been proven correct CS. And it appears he can only read one sentence and not comprehend the article.

Why not cut the 'retrospective' stuff Curie...

Just put up your alternative and we'll discuss your 'way better' system...

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22 minutes ago, Thomass said:

Oh my...says someone who can't understand basic "retrospective" Englaise...

All one needs to read in this Racing rant from your 'James' ( obviously you know him) is the last conclusion...

"it isn't possible to make a definitive case" after his 'massive' 5 years...

Yea that...why doesn't he write his own 'Handicapping Shang Gree La' then...

...like you and your Besty did for NZTR...who binned it as unworkable...

It wouldn't have included a wide range by any chance...which would have seen even more of a mass exodus to Aus. with a less severe system that's acceptable to most stakeholders??

Perhaps you'd be so kind to put your ideas up here on what you'd proposed and we'll disect the 'document'

Im hoping it'll include an acknowledgement that the physiological difference between not only immature age horses is there...but the fact females are physiologically smaller on average as well...

Perhaps your 'system' will include the ability to weigh each participant and/or include the exact birth dates instead of a one fits all option?

cant wait...thanks

Nope. Wrong. don't know him.

Never wrote any handicapping proposal for NZTR or anyone else. Wrong.

The sentence you read, if you'd read the rest of the article, was based on what I've already told you. You can't draw that conclusion ... without also adjusting for the ability of each runner, which we did, and could reach the conclusion that the female allowance (or something) was biasing results in favour of females (in handicap races), so you are wrong again.

Edited by curious
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26 minutes ago, Thomass said:

Why not cut the 'retrospective' stuff Curie...

Just put up your alternative and we'll discuss your 'way better' system...

The alternative was put up by Carpenter in a previous review and binned by NZTR. Our evaluation simply showed that the binning had worsened the impact of the handicapping system cf. what handicapping systems are supposed to do, i.e. equalise the chances of all runners.

The alternative to achieve that or something close is simple.

  • Scrap the female allowance and handicap/rate all horses on demonstrated recent ability.
  • Ensure that horses are re-rated much more quickly in both directions to a level where they are competitive.
  • Have say a 7.5kg weight spread (1.5kgs per rating point) in each rating band to get rid of the bias in favour of higher rated/better horses.
  • Pilot that, review and adjust as required.
Edited by curious
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15 minutes ago, curious said:

Nope. Wrong. don't know him.

Never wrote any handicapping proposal for NZTR or anyone else. Wrong.

The sentence you read, if you'd read the rest of the article, was based on what I've already told you. You can't draw that conclusion ... without also adjusting for the ability of each runner, which we did, and could reach the conclusion that the female allowance (or something) was biasing results in favour of females (in handicap races), so you are wrong again.

So you did this for them unsolicited?

"Exactly what you and I did when we examined the NZ handicapping data pre and post the rating changes for NZTR. Except that we were able to go a step further by using current ratings as a proxy for ability as well"

Did it find the female allowance unfair...and did you recommend anything as an alternative other than return to the previous system?

What the neysayers appear to be wanting in all of this is not a Weight for Age/sexes system...

..but a Weight for Abilty one...

Winx's superior cadence 'ability' receives 5 kegs more than a physiologically superior Stallion with less cadence and /or stride..which results in a blanket finish

Obviously what WFA Racing is about...

...is evening up chance by acknowledging physiologically inferior characteristics at different/permanent stages rather than actual ability...

...which should provide us with a Championship winner

 

 

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44 minutes ago, Thomass said:

So you did this for them unsolicited?

No. I was asked by Purcell.

44 minutes ago, Thomass said:

Did it find the female allowance unfair...and did you recommend anything as an alternative other than return to the previous system?

Not necessarily unfair, but that it may have been contributing to changes in the results (and possibly the racing population) for both genders.

No recommendations.

p.s. I keep attributing the 2011 review to Carpenter. It was Mark Webbey sorry.

Edited by curious
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So in your opinion what will 2 kgs translate into ground gained?

And do you recognise the physiological differences between an average Staillion and Mare results in a physically smaller mare version by @ 40/50kgs on average?

Take 2 first starters...a Colt and Filly..both born the same day...

If starting off at level weights without a Fillies allowance, the physically superior Colt should win...

What becomes immediately apparent is the Colt will progress to the next Rating band...while the filly stays in the same band...

And that's your problem with "handicapping on shown recent ability"

Our system of mixing sexes, will have a bunch of inferior mares at the bottom of a Rating band, struggling to go through to the next level,  when they're denied an opportunity to race with a balancing up of the physiological negative.

 

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4 hours ago, Thomass said:

Says someone who can't read basic race results..and doubles down when it's pointed out..next

btw why are you starting new threads when a topic has already been established?

weird

Don't bite the hand the feeds your insatiable demand for attention.

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1 hour ago, Thomass said:

So in your opinion what will 2 kgs translate into ground gained?

Between .05 and .2 of a length but it varies depending on ground etc.

1 hour ago, Thomass said:

And do you recognise the physiological differences between an average Staillion and Mare results in a physically smaller mare version by @ 40/50kgs on average?

Yes.

1 hour ago, Thomass said:

If starting off at level weights without a Fillies allowance, the physically superior Colt should win.

Why? The filly has 50kgs of body weight less to carry. But if you look at the data in the above study, yes, the male will tend to be more likely to win.

1 hour ago, Thomass said:

Take 2 first starters...a Colt and Filly..both born the same day...

If starting off at level weights without a Fillies allowance, the physically superior Colt should win...

What becomes immediately apparent is the Colt will progress to the next Rating band...while the filly stays in the same band...

If they are first starters, they'd likely be in a maiden race, not a handicap. I didn't say there should not be an allowance in set weight races such as maidens.

1 hour ago, Thomass said:

And that's your problem with "handicapping on shown recent ability"

Our system of mixing sexes, will have a bunch of inferior mares at the bottom of a Rating band, struggling to go through to the next level,  when they're denied an opportunity to race with a balancing up of the physiological negative.

Actually, that's exactly the reason why you need a greater weight spread within the rating bands. Nothing to do with sex but to mitigate the advantage that higher rated horses have with the current system. Then, if horses can't win from the bottom of the rating band, they have probably reached their level in the handicap system and unless they can drop back or some other system is available to cater for them, e.g. claiming races, they probably need to find a new career.

Edited by curious
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1 hour ago, curious said:

Between .05 and .2 of a length but it varies depending on ground etc.

Yes.

Why? The filly has 50kgs of body weight less to carry. But if you look at the data in the above study, yes, the male will tend to be more likely to win.

If they are first starters, they'd likely be in a maiden race, not a handicap. I didn't say there should not be an allowance in set weight races such as maidens.

Actually, that's exactly the reason why you need a greater weight spread within the rating bands. Nothing to do with sex but to mitigate the advantage that higher rated horses have with the current system. Then, if horses can't win from the bottom of the rating band, they have probably reached their level in the handicap system and unless they can drop back or some other system is available to cater for them, e.g. claiming races, they probably need to find a new career.

So infinitesimal difference then....even though the experienced BHA handicappers believe otherwise?

So you think less body weight translates into being faster and fleet of foot as well?

Thats counterintuitive however...the superior physiologically developed Male will be always too strong...

Then, 2 horses re handicapped for a similar win and the more robust horse (Stallion) will be less affected when anchored with heavier weights..especially over longer distances...

Its a common narrative...that of a Male with 'weight carrying ability'...very seldom Youll hear of the opposite sex...

Almost all first starters in Australasia are starting in Set Weight Maiden races though...and it provides a very good start for a Female to enable a fair transition through the Rating bands...

...rather than starting off behind the eight ball...

So let's take your example of even weights if they start off in a Handicap...

You acknowledge a Colt v Filly having their first starts will be at level weights in a Handicap then?

 

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So the physiologically superior Colt carrying the same weight beats the Filly by 0.2L and proceeds to the next grade and onto greater Premier Racing riches...

...while the Filly remains in the same grade battling superior built Colts on the same Handicap again

Meanwhile In the other World of Ratings based Handicapping with Female allowances...Myrtle has at least an even chance of beating Bertyl with an allowance and progressing into the next grade...

..with TRANSPARENT Ratings included while receiving a fair allowance to enable a smoother transition...

Denying there's an advantage to physiologically superior animals in Colts over Fillies and you'll also be denying a younger AGE animal needs a weight allowance to compete fairly..

..which is what we give 3yo's on a sliding scale through the season in Rating's based Handicaps agin Older horses...as well as WFA...

To deny any of that is to deny the Admiral even existed and he should have been a Cabin Boy...

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1 hour ago, Thomass said:

So the physiologically superior Colt carrying the same weight beats the Filly by 0.2L and proceeds to the next grade and onto greater Premier Racing riches...

...while the Filly remains in the same grade battling superior built Colts on the same Handicap again

Wrong again. Under my revised handicapping system the filly which finished .2 lengths from the winner would be re-handicapped in line with it's performance and the ratings of the horses it beat or that finished just ahead of it.

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1 hour ago, Thomass said:

Meanwhile In the other World of Ratings based Handicapping with Female allowances...Myrtle has at least an even chance of beating Bertyl with an allowance and progressing into the next grade...

..with TRANSPARENT Ratings included while receiving a fair allowance to enable a smoother transition...

Denying there's an advantage to physiologically superior animals in Colts over Fillies and you'll also be denying a younger AGE animal needs a weight allowance to compete fairly..

 

Wrong again. Mertyl has close to an even chance of beating Bertyl as it is (on average). And once there is performance to base handicapping on then that's what should be used. Handicapping must be based on INDIVIDUAL performance assessment, not averages for sex or age. That defeats its whole purpose. In fact it's plain stupid if you want competitive racing, punter interest and increased revenue.

Edited by curious
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5 hours ago, Thomass said:

To deny any of that is to deny the Admiral even existed and he should have been a Cabin Boy..

I'm not sure that it is me that relegated the Admiral to cabin boy. He thought that 2yos should have a 10kg+ allowance from 3yos, right? What did NZTR decide to give them? 2kgs?

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16 hours ago, curious said:

Wrong again. Under my revised handicapping system the filly which finished .2 lengths from the winner would be re-handicapped in line with it's performance and the ratings of the horses it beat or that finished just ahead of it.

Oh blardy marvellous....

So another first start Colt comes along of equal ability to the other Colt...who beat the Filly on level weights...

...and meets the Filly with the re-Handicap for running 2nd...on even better terms to the first Colt...

...you're not too good at this 'Handicapping' are you?

Heres another conundrum for you...

3 Horses finally meet in a Race...all on Rating 70...a 4yo Colt....a Mare who's so far started in 2 Mares only races...and an early season 3yo filly who's also started only in her age group...

Would you start all horses off the same weight with their 70 rating?

 

 

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15 hours ago, Chief Stipe said:

Exactly Curious.  Why should Melody Belle automatically get a 2kg advantage?  Not that 2kg makes much of a difference.

You do what Ellis did...realising our racing has depleted top class Males...the Blue Bloods sold at yearling sales...

...go buy a speedy Australian bred mare who usually dick our slower Mares...

You can't adjust a system every couple of years to suit the flavour of the time....

...and you think 2 kgs = 0.2L as well Maestro?

 

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12 hours ago, curious said:

I'm not sure that it is me that relegated the Admiral to cabin boy. He thought that 2yos should have a 10kg+ allowance from 3yos, right? What did NZTR decide to give them? 2kgs?

Under the WFA scale NZTR gives them up to 10.5 kgs or 12.5 kgs for fillies.

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