Published online by Cambridge University Press: 01 January 2025
The present paper shows that the usual factor analytic structured data dispersion matrix Λ Ψ Λ’ + Δ can readily arise from a set of scores y = Λ η + ε, where the “common” (η) and “unique” (ε) factors have nonzero covariance: Γ = Cov(ε,η) ≠ 0. Implications of this finding are discussed for the indeterminacy of factor scores, and for the issue of invariance of factor analytic covariance models. The size of the problem is explored with numerical examples.
I would like to acknowledge the large amount of effort and stimulating input supplied on the previous drafts of this paper from the reviewers, Associate Editor, and Editors of Psychometrika. Particular thanks go to William Meredith for his assistance with the final draft.