Predicting a nag’s distance ability from its pedigree is actually not a bad idea. The way dosage goes about it is unnecessarily convoluted, as well as lacking in common sense.
One such scheme is contained in Bloodstock Breeding, a wonderful reference book from many decades ago by Sir Charles Leicester. I recommend this book in its entirety wholeheartedly, particularly that section on predicting distance ability from pedigree.
Dosage bases its predictions 100% on sires. That is a problem in itself, ignoring the genetic contributions of all mares. For right now I will let this problem slide, but I will return to it at the conclusion of this post.
Dosage bases its predictions only on SOME sires, those it calls chefs-de-race (French for “chiefs of the breed”). This is another problem. It would make a lot more sense if it were based on all sires in a given pedigree.
The chefs in a given pedigree are given points: 16 for the sire, eight for the two grandsires, four each for the four sires in the third generation, and two each for the eight sires in the fourth generation.
If all 15 sires in the first four generations of a pedigree are chefs, that pedigree has the maximum total of 64 dosage points. Such pedigrees do exist, but they are extremely rare. And some nags have zero points in their pedigrees. These nags are not quite so rare.
The average for the breed is a little over 20 total dosage points per pedigree. So dosage predictions utilize less than a third of the available points on average.
Needless to say, this is another problem. If dosage proponents were honest, they would say something like the lower the number of total points in a pedigree, the less confidence we have in the predictions. And conversely, the higher the number of total points in a pedigree, the more confidence we have in the predictions.
Dosage proponents do NOT say anything like this. They are reluctant to admit any possibility of error (just like any believers in any “true” religion).
The late Jack Werk was at least honest enough to address this issue. He said something like a minimum of 18 dosage points in a given pedigree was necessary in order to have any confidence at all about a dosage prediction. I applaud that honesty and agree with this statement. And 18 seems about the right number to me.
Better nags tend to have more dosage points than not-so-good nags. This is merely a tendency, not a strong correlation. Many good nags have less than 18 total points, and many bad nags have more than 18 total points.
Quiz time. One North American classic winner (Derby, Preakness, Belmont) within the last 30 years had only six dosage points in its pedigree. Can anyone name that nag????? Answer at the conclusion of this post.
Now let us return to the original problem of excluding all females from dosage calculations. Dosage proponents say that this is not a problem because the contributions of females are captured via their sires. As usual, they are full of shit.
A good way of illustrating this problem is with Zenyatta, specifically foals out of Zenyatta. I think most people would agree that Zenyatta should be an excellent source of stamina in any pedigree. The longer the race, the better she liked it. Although she never raced beyond a mile and a quarter, she appeared to be just getting warmed up at that distance.
Zenyatta was by Street Cry (not a chef). Street Cry was by Machiavellian (not a chef). Machiavellian was by Mr. Prospector (chef). Zenyatta was out of a mare by Kris S. (not a chef). Kris S. was by Roberto (chef).
The other two sires in Zenyatta’s third generation are Troy (not a chef) and Forli (chef). Although not a chef, Troy was a dual classic winner and a sire of classic winners and clearly a good influence for stamina.
Since we are talking about foals out of Zenyatta and dosage considers only four generations of a pedigree, only the first three generations of Zenyatta’s pedigree are material here. So for dosage purposes in this case Zenyatta’s pedigree boils down to Mr. Prospector, Roberto, and Forli. All three names are common in all pedigrees (particularly Mr. Prospector).
So whatever made Zenyatta uniquely Zenyatta, you cannot find it in any dosage interpretation of her pedigree or the pedigree of her foals. Dosage proponents are full of shit when they claim that this is NOT a problem, that the contributions of mares are captured through their sires.
Indeed, this is such a problem that you would be justified in rejecting dosage on these grounds alone, that it ignores all females in all pedigrees.
The answer to the quiz question above is Snow Chief, winner of the 1986 Preakness Stakes and champion three-year-old. Snow Chief was by Reflected Glory out of Miss Snowflake, by Snow Sporting. Reflected Glory was by Jester. Jester was by Tom Fool out of Golden Apple, by Eight Thirty.
The only two chefs in Snow Chief’s entire pedigree were Tom Fool and Eight Thirty. That is six dosage points out of a possible total of 64 (males only). Jack Werk would have said that the confidence of any dosage prediction about that pedigree was close to zero. And he would have been right.
Dosage purists blithely ignore all this common sense. The dosage numbers are scripture to them, no matter how many or how few points are involved. To reiterate a previous point, dosage proponents are reluctant to admit any possibility of error (just like any believers in any “true” religion).