Summary: Principal component analysis (PCA) and factor analysis (FA) resemble each other but have rather different aims. However, PCA is used very often for the same purpose as FA without careful consideration. The present paper is an attempt to answer the following questions: (1) Can a substitute use be justified? (2) What attention should be paid to interpreting loadings calculated with PCA? Some results and typical tendencies in monofactor cases for a population are presented. Further, these are examined for certain empirical data.