Abstract of Humphries, J.M., F.L. Bookstein, B. Chernoff, G.R. Smith, R.L. Elder, and S.G. Poss. Multivariate discrimination by shape in relation to size. 1981. Syst. Zool. 30(3):291-308.

The sheared pc method is presented as an alternative to discriminant function analysis for separating the effects of size and shape in morphometric discrimination. Unlike DFA, sheared PCs preserve the ordination of cases without distorting the contribution of each character to each PC.