a1 CSIRO, Division of Mathematical Statistics, Rural Sciences Laboratory, Private Bag, P.O., Wembley, Western Australia, 6014
a2 Biometrics Unit, Institute of Agriculture, University of Western Australia, Nedlands, W.A. 6009
The aim of this paper is to help biologists gain a clearer understanding of what is involved in covariance analysis. It is an exposition on the derivation of the regression coefficient in the analysis of covariance, and hence on the interpretation of the covariance adjustment. The covariance adjustment is shown to be equivalent to regressing the residuals from an analysis of variance of the original variate on the residuals from an analysis of variance of the covariate.
(Accepted April 03 1973)