ON THE ASYMMETRY OF BIOLOGICAL FREQUENCY-DISTRIBUTIONS

The long‐standing problem of determining whether the skewness in a sample frequency distribution is the manifestation of the intermixing of disparate groups characterizable by a normal mixture distribution or the manifestation of non‐mixture, skew‐producing determinants is discussed. Biometrical tools for modeling and quantifying the significance of the skewness in a trait of interest that invite interpretations other than those formed in mixtures or “subgroups” are elaborated. Statistical methods for testing whether a normal mixture distribution better characterizes a set of data than the proposed (or any other) skewed, single‐population‐oriented models are offered. The power of these tests is examined through Monte Carlo experimentation. A brief application in hypertension research demonstrates some of the problems and methods discussed in the paper. Copyright © 1990 Wiley‐Liss, Inc., A Wiley Company