On an Approximate Test for Homogeneity of Coefficients of Variation

Abstract

The coefficient of variation (formula presented) or ratio of standard deviation to mean (formula presented), is a useful parameter and measure of variability in certain situations since it is expressed in absolute units. Thus in comparing results on repeated clinical data when k (≥ 2) different measurement techniques are utilized in analyzing the same or paired specimens, it is of interest to compare the corresponding sample c. v.' s Zl, …, Zk, respectively for the k techniques. For this situation the following note presents a test which is based on McKay' s approximation [4J to the distribution of the sample c. v. for the normal distribu-tion, and utilizes Pitman' s method [5J for the hypothesis of equality of scale parameters of Gamma variates.