Kentucky Derby Dosage explained, debated

With the Derby picture still somewhat muddled, it's time to bring out those arcane statistical tools to try and figure out who the heck might win Kentucky Derby 137.

One of the tools that always pops up during Derby season is the Dosage Index.  When I first started falling in love with racing a few years ago, I kept seeing this Dosage Index mentioned in articles about the Derby, but I had no clue what they were talking about.  Even as I learned that it was a measure of the proclivity for a horse to get a certain distance, I still didn't understand exactly how it worked.  I just knew it was a number.

But as a student in the University of Louisville Equine Business Program (graduating in May!), one of the many benefits is a much greater understanding of things like the Dosage Index.  So, I shall try to explain the Dosage Index here to those who may not have a complete grasp on how it is measured.  And for others who couldn't care less about such statistical measurements, you can at least see the names of the top Derby contenders and start thinking about whom you might want to bet on.

The original idea of Dosage was developed by French cavalry officer JJ Vuillier, who believed that certain sires exerted extraordinary influence on Thoroughbreds.  Since he was French, he called them "chefs de race."  Later, the Italian Dr. Franco Varola followed up on Vuillier's theories and categorized these sires as Brilliant, Intermediate, Classic, Stout (now Solid) and Professional.  Essentially, Brilliant means sprinter.  Classic means 1 1/4 miles, the distance of the Kentucky Derby.  And Professional suggests a two-mile distance pedigree, something rarely seen in the U.S. these days.  Sprinters almost never last 1 1/4 miles.  Professionals can rarely go fast enough to compete at 1 1/4 miles - you get the idea.

An American adherent to the theory was Dr. Steve Roman, who has continued to update the "chefs de race" lists and Dosage Index to this day.

So here's how to calculate a runner's Dosage Index:  First, access his five-cross pedigree at Equineline.com.  Type in the horse's name and the pedigree will appear.  Look through the horse's pedigree for four generations and mark the chefs de race, which can be found here.  Beside each chef de race name will be a B or an I or a C or S or a P, which signifies the categories listed above (Brilliant, Intermediate, Classic, Solid, Professional).  Some horses have two categories listed.

Early Derby favorite Uncle Mo's pedigree looks like the following.  Uncle Mo is in the far  left blue block.  His dam and sire take up the two blocks to the right, with the sire on top.  Their parents take up the third block.  With Dosage, you are only concerned with the blue blocks (the sires), and while you probably can't read the names, look it up for yourself and you'll see the sires in his bloodlines.  For Dosage, you only go back four generations, so the right-most block here is ignored.

The formula goes like this:  The first generation (Uncle Mo's father) counts for 16 points.  So, if Indian Charlie is a chef de race, he gets a 16.  In this case, Indian Charlie is not, so the score is zero.  The second generation is allotted 8 points each (sire's sire and dam's sire).  Again, in this case, neither is a chef de race.  Same for the third generation, where each sire counts for 4 points.  In his fourth generation, he has four chefs de race (two points each):  Caro, Roberto, Danzig and Northern Dancer.  For each sire, the two points are divided up by their proclivities as mentioned above.  So Uncle Mo's chart looks like this:



Caro's two points are distributed:  One point to Intermediate and one point to Classic.  Roberto is a pure Classic runner, so he gets two points in Classic... and so on.

To calculate the Dosage Index, you add the Brilliant plus the Intermediate plus 1/2 the Classic divided by 1/2 Classic plus Solid Plus Professional.  In other words, B + I + 1/2 C/1/2 C + S + P.  In this case, the result is 1 + 2 + 2.5 divided by 2.5 + 0 + 0 = 2.20.  So, Uncle Mo's Dosage Index is 2.20.

The idea is to get as close to 1.0 as possible because that indicates a perfect balance of speed and stamina.  It is virtually impossible to achieve a perfect 1.0, and that is why winning the Kentucky Derby is so difficult.  The 1 1/4-mile distance of the Derby is essentially the point at which horses cross the barrier of speed to stamina.  It is extremely, extremely difficult for a horse to run for two minutes at a sprinter's speed because sprinting is an anaerobic activity and running a longer distance is an aerobic activity.  The buildup of lactic acid fatigues the muscles and by two minutes, horses get too tired.  This is why you can't "buy" the Derby.  The combination of speed and endurance is almost impossible to predict, and that's why Secretariat only comes along once in a generation, if that often.

The Dosage Index has been criticized as bunk, and as a handicapping tool, it is essentially useless.  But, contrary to its continued usage in the Daily Racing Form and other places, it was not designed to predict the winner of races.  It was designed to calculate the probability of a certain horse to get a certain distance.  That is all.  I repeat, that is all.  And in that respect, it is still a decent measurement.

A second tool is the center of distribution.  I will not bore you with the calculations of that one, but the important rule of thumb for that statistic is that the closer you get to zero, the more in balance speed versus stamina.

Finally, Roman introduced the concept of "dual qualifiers," meaning horses that were within ten points of the top-weight in the Experimental Free Handicap (or EFH) in their two-year-old seasons AND had a Dosage Index of 4.0 or less.  The EFH gives a rating to the top two-year-old runners in an attempt to assess their potential for the Triple Crown the following year.  For many years, Roman touted the fact that no horse with a Dosage Index of higher than 4.0 had won the Kentucky Derby, and this proved true for a while, but in recent years, a few horses have debunked that theory.  Plus, many of the recent Derby winners haven't even been weighted on the EFH, so these tools have seriously come into question.

However, since they were never intended as handicapping devices and since they still give some indication of a horse's proclivity to get a certain distance, they are still useful in the proper context.

So without further adieu, here are the Dosage Index results and Centers of Distribution for this year's top Kentucky Derby contenders, ranked in order of the most recent Paulick Derby Index:

It's very difficult to draw conclusions based on these statistics alone, but if one were to weigh them against the performances so far, Uncle Mo still looks pretty darn impressive.  Dialed In's numbers don't scream DERBY WINNER, but his visual performances have been of high quality so far.  And the numbers on Archarcharch and Santiva are certainly intriguing.  Not to mention Animal Kingdom, who has yet to run on dirt.  Food for thought?