 The term "Lexis ratio" is sometimes referred to as "L" or "Q", where

Where formula_2 is the (weighted) sample variance derived from the observed proportions of success in sets in "Lexis trials" and formula_3 is the variance computed from the expected Bernoulli distribution on the basis of the overall average proportion of success.Trials where "L" falls significantly above or below 1 are known as "supernormal" and "subnormal," respectively.This ratio ( Q ) is a measure that can be used to distinguish between three types of variation in sampling for attributes