What is the Purdy formula prediction?
The Purdy point system is calculated from a table of running performances compiled in 1936 called the “Portuguese Scoring Tables.” These velocity measures were intended to be maximum possible velocity in a straight line. Each of these performances was arbitrarily given a Purdy score of 950. (World record times in 1970 have about 1035 Purdy points.) Purdy subsequently estimated an equation for the men’s world record performances (as of 1970). This enabled Purdy points to be estimated using the equation rather than the Portuguese tables. The Purdy formula is often quite different from the other predictions; and so it has been excluded from the calculation of the average.
