It is generally accepted that in the United States and other modern industrial societies there is a link between formal schooling (number of years of formal education) and social mobility, though some scholars such as Anderson, Blau and Duncan, and Jencks have disputed the strength of this link. The study of educational plans (or "educational expectations") of secondary school students in such societies derives its significance in part from findings of social scientists such as Hauser and Sewell et al.  that a positive relationship exists between educational expectation and educational achievement, the latter being measured by number of years of formal schooling received. In order words, the investigation of educational expectation is valuable partly because it is a predictor - albeit a somewhat crude one - of ultimate educational achievement and hence socio-econmic status.