Robust Promin: a method for diagonally weighted factor rotation

Oblique rotation of factors is usually performed in exploratory factor analysis in order to achieve the best and simplest interpretation of the solution based on the prescribed number of factors. Currently available algorithms, however, do not take into account the fluctuation of the correlations on which the factor solution is based. If such correlations’ stability is low, the rotated solution obtained in a specific sample may substantially differ from the rotated solutions obtained in different samples from the same population. The present paper proposes a modified version of the Promin rotation designed to achieve simple and stable rotated solutions through the samples. The usefulness of Robust Promin is illustrated by using an empirical example based on a real dataset. The procedure proposed in this paper has been implemented in the FACTOR factor analysis program version 10.9