Key points are not available for this paper at this time.
Jöreskog's (1970a) procedure for the analysis of simplex models was used to test Humphreys' (1968) assertion that eight semesters of undergraduate grade-point averages have a simplex form. Not only was this assertion confirmed but precise estimates of reliability and of unattenuated correlations were obtained.
Werts et al. (Sat,) studied this question.