"There is no law by which you determine class or classify horses. An intimate knowledge of a horse alone tells what he has done and how he has done it, places him, and nothing else."
From a handicapper's perspective, the competition a horse has defeated, the recency and the strength of those victories, as measured by running time, margin of victory, and perseverance in the stretch; can be a good starting point when evaluating Class.
Further, Speed figures, Pace ratings, Current Form, and performances in Grade 1 and Grade 2 stakes; can be additional indicators of Class.
Class barriers are more rigid on turf than dirt. In the late stages of turf races, the winning horses will need to combine the three elements of Class; Speed, Stamina, and Determination.
Moreover, we view Thoroughbred Class as sharing an interdependent relationship with every handicapping factor; thus forming a delicate interweave which will become the horse's ultimate expression of its Class on race day.
Consequently, we attempt to quantify Thoroughbred Class by evaluating each Primary Factor independently (rating), and in relationship to all factors (weighting); insofar as they contribute to the horse's Class (estimating).
The resulting numerical value attributed to each horse represents our best attempt to estimate its probabilty of winning, based upon its Class, Breeding, Speed, ability to sustain a Pace and Current Form; as influenced by the Secondary and Unknown Handicapping Factors.