# LOD scores

The LOD (logarithm of odds) score is the statistical test most used in genetic linkage calculations (indicating the likelihood of linkage vs. non-linkage).

Specifically:

If two markers are unlinked, then the odds (O_{u}) of getting exactly x recombinant progeny and y parental-type progeny is: (0.5^{x})(0.5^{y}).

If the markers are linked, with a recombination frequency of r, then the odds ratio (O

_{L}) is given by (r^{x})[(1-r)^{y}].The odds ratio is O

_{L}/O_{U}and the LOD score is log_{10}(O_{L}/O_{U}).