The structure of improper solutions in maximum likelihood factor analysis (Q1819505)

The structure of maximum likelihood estimators in the Heywood case is investigated without any restrictions on parameters. It is shown that this structure is identical to that obtained by \textit{K. G. Jöreskog} [Some contributions to maximum likelihood factor analysis. Psychometrika 32, 443-482 (1967)] under the restriction that some uniquenesses are zero. As a result, the structure of generalized least-squares estimators is clarified.