An explicit formula for the Kolmogorov‐Smirnov statistic, when distribution parameters are obtained from the data, does not exist in the literature. Lilliefors(5) provided a table of the Kolmogorov‐Smirnov statistic by a Monte‐Carlo simulation technique in which the sets of random samples determined the sets of parameters. This paper applies the 4‐parameter lognormal (SB) model defined by Johnson(6) to these Monte‐Carlo data and shows that the Kolmogorov‐Smirnov statistics can be described by this model which is constrained to the interval zero‐one.