Turning RF into map distances
The unit of measure of recombination frequency is the centimorgan (cM), named after the geneticist Thomas Hunt Morgan. A distance of 1cM between two loci represents the situation where the probability that they will be separated by recombination during one round of meiosis (and thus inherited separately) is equal to 1%
There are two mathematical formulae for converting recombination frequency into cM, the Haldane and the Kosambi mapping functions (named after their creators). They give similar outcomes, particularly for small values of cM. The Kosambi function is generally seen as more accurate, as it contains a correction for double crossovers (see next slide).