The minimum average correlation between equivalent sets of uncorrelated factors

A simplified proof of a lemma by Ledermann 1938], which lies at the core of the factor indeterminacy issue, is presented. It leads to a representation of an orthogonal matrixT, relating equivalent factor solutions, which is different from Ledermann's 1938] and Guttman's 1955].T is used to evaluate bounds on the average correlation between equivalent sets of uncorrelated factors. It is found that the minimum average correlation is independent of the data.This paper owes much to an unknown reviewer.