In the previous chapters I have examined and explicated the computations and nature of factor analysis. I have scrutinized different methods of condensation and discussed factor rotation. The problems of the indeterminacy of factor analysis, the infinity of mathematically equivalent solutions, the difficulties of replication and the need for simple structure have been described. All this led to a prescription for technically sound factor analyses, a prescription with which many psychometrists have essentially concurred. All this, of course, was factor analysis in the exploratory mode.