Interaction of All Factors
All of the above' factors interact in ways impossible to measure. As an example, how should we interpret the findings of Jencks's study of the earnings of brothers? He found that brothers raised in the same family who made similar test scores and who had the same amount of schooling and work experience made greatly. different earnings, with _ . one brother often making twice as much as the other. This variation in earnings between' these carefully matched brothers was at least 80 percent of the variation among a random sample of unrelated persons [Iencks, 1979, p. 293}. It is likely that all the above mobility determinants are involved, and luck may not be the least of them. This discussion of mobility determinants has centered upon upward mobility. How about downward mobility? The same determinants also produce downward mobility . . The structural factors-such as declining in dustiest, a stagnating economy with declining productivity, a declining rate of economic growth and technological change-tend to increase the total number of persons who must lose class status. The individual factors- education, work habits, luck, and the others-s-determine which persons suffer class status decline.