The appropriateness of sum scores as estimates of factor scores in the
multiple factor analysis of ordered-categorical responses
Abstract
Unit-weight sum scores (UWSSs) are routinely used as estimates of factor
scores on the basis of solutions obtained with the non-linear
exploratory factor analysis (EFA) model for ordered-categorical
responses. Theoretically, this practice results in a loss of information
and accuracy, and is expected to lead to biased estimates. However, the
practical relevance of these limitations is far from clear. In this
article we adopt an empirical view, and propose indices and procedures
(some of them new) for assessing the appropriateness of UWSSs in
non-linear EFA applications. A new automated approach for obtaining
UWSSs that maximize fidelity and correlational accuracy is proposed. The
appropriateness of UWSSs under different conditions and the behavior of
the present proposal in comparison with other more common approaches are
assessed with a simulation study. A tutorial for interested
practitioners is presented using an illustrative example based on a
well-known personality questionnaire. All the procedures proposed in the
article have been implemented in a well-known noncommercial EFA program.