# Lexis ratio

$L^2 =Q^2 = \frac{s^2}{\sigma_0^2}.$
Where $s^2 \,$ is the (weighted) sample variance derived from the observed proportions of success in sets in "Lexis trials" and $\sigma_0^2$ 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.