Aproksymacja wartości krytycznych testu Manna-Whitneya dla małych prób

Abstract

The article deals with important, from the point of view of application, Mann-Whitney test used for comparing distribution of two populations. After a short review of the known from literature basic properties of the test’s statistic, a definition of randomized test and interpolated quantiles is given. Then a simple and at the same time quite exact (for a sample of the size 5 ≤ n ≤ 50) approximation of these quant i les is presented, due to which the using of tables becomes needless. Moreover, it has been proved that the recommended in many works approximation by means of normal distribution leads to large errors in the sample size.