Classification schemes and the study of social mobility: A detailed examination of the Blau-Duncan categories

The Blau-Duncan system of seventeen occuptational categories has frequently been used as the basis for the study of social mobility patterns in the contemporary United States. In this paper, we examine the validity of these categories by subdividing them in various ways and examining the mobility flows in this more detailed classification. Initial log-linear and cluster analyses using data from the Occupational Changes in a Generation II (OCG-II) survey suggest that the Blau-Duncan scheme hides certain patterns of social structuration, and we form new classification systems on the basis of these results. However, cross-validation analyses using the cumulative General Social Survey data set show that the improvements associated with our schemes do not generalize beyond the OCG-II data. Thus, we recommend continued use of the Blau-Duncan categories, given that they have been employed so often in previous work.