Sister Sarah Games the Fix
by Roger Lyons
My last post demonstrates the internal dynamics of the dam line index (DLI), with its seven-generation search limit and its survey of the last fifteen years of SWs (in the original analysis). Narrowing the survey parameter to SWs of the last 10 years confirmed the expectation that the number of SWs tracing to early-era dams would decrease substantially while their average generational distance would increase somewhat–a formula for declining DLIs of early-era dams relative to the late-era dams. Accordingly, the early-era dams moved down in rank as the late-era dams moved up, very dramatically in many cases.
But, as Greg Michalson comments, Sister Sarah (Abbots Trace-Sarita, by Swynford), an important dam born in 1930, proved non-compliant. She actually moved up in rank from eighth to sixth. The fix against her is strong statistical medicine, and, in order to game it, she would need to pick up a one- or two-generation advantage somewhere along the line over other older mares. Baby League, for example, born five years later than Sister Sarah, dropped from 14th to 18th.
Nothing proves a powerful rule like a notable exception, and Sister Sarah is–well–no exception. The numbers provide presumptive ground for suggesting that this family might be more capable than most other families of producing quality in old age. I can’t think of any other way Sister Sarah could beat the statistical fix I put her in.
Even her first generation suggests this. Her second-most substantial contributor to SWs since 2000–behind Sybil’s Sister (1943)–was her daughter, The Veil, born when Sister Sarah was 23 and the latest-born branch of the line. She’s represented within six generations (puts Sister Sarah in the seventh) by 26 SWs in the 10-year group, down from 36 in the 15-year group. The late coming of The Veil assured Sister Sarah a generational advantage over other mares of her era when the first decade of the 21st century rolled around.
Now, Sister Sarah’s daughter Lady Sybil was born in 1940 when the former was only ten years old. Even so, Lady Sybil retained a large proportion of SWs in the 10-year survey. Of the 22 that had Sister Sarah within seven generations of the 15-year group, 15 also qualified from the 10-year group. That’s the branch from which Workforce (2007) descends–his sixth dam Sister Sarah’s daughter, Lady Sybil.
Lady Sybil had a 1952 daughter named Esquire Girl, by My Babu, which produced Workforce’s fourth dam, Sounion (1961), by Vimy. At age 20, Sounion produced the 1981 filly Media Luna, by Star Appeal and the third dam of Workforce. By virtue of Sounion’s production of Media Luna in old age, Workforce and eight other winners of stakes run after 1999 descend from Sister Sarah within the seven-generation limit.
No doubt, such occurrences can be found along the branches descending from any great dam, but the numbers suggest that, more than is usual, descendents of Sister Sarah have been able to produce good producers late in their breeding careers.
Thanks for this follow up, Roger. Among the many extra virtues of studies like yours is that when anomalies or outliers or even merely unexpected and intriguing results show up you can often learn something by looking at the individual situations that account for them.
November 5th, 2010 at 4:36 pmGreg, I would undoubtedly have missed that Sister Sarah angle if you hadn’t mentioned it. Good eye.
November 5th, 2010 at 5:35 pm