Let me begin by first explaining that one of the meanings of the word 'handicapper' is 'someone who believes that it is possible to equalize performances of two racehorses of differing ability by assigning relatively higher handicap (read 'weight on a horse's back) to the better horse of the two. In that sense, each serious student of form--including the official Handicapper of a race club whose job is to try and equalize the chances of competing horses by assigning them different weights--employs some math to arrive at that figure.

Most racegoers take the weights assigned by the official handicapper of the club very seriously, and even horse trainers are not an exception. In fact, some trainers make use of apprentice riders (also called 'bug boys') who are allowed to claim an allowance (a concession in weight) when they feel lesser weight would enhance their horse's chances.