A Structural Model of the Mobility Table

We propose a multiplicative (log-linear) model for mobility tables (or other cross-classifications) which is helpful in locating cells where counts are especially dense or sparse. This specification eliminates the confounding of main effects and interaction effects, which has plagued many other methods of measuring and interpreting association in mobility tables, especially those methods based on the model of simple statistical independence. The model yields a parsimonious set of parameters which describe the table, and goodness of fit can be assessed with standard inferential procedures. For each cell of the table the model yields a useful measure of association, which we call the new mobility ratio. We illustrate the model by reanalyzing the classic British mobility table of 1949, and we use that example to compare our measure of association with other mobility measures. Occupational mobility is a fundamental indicator of the temporal aspect of social stratification (Duncan, b). The centrality of occupational roles in the organization of contemporary and especially industrial societies is coupled with strong commonalities across time and space in the differential access of occupational incumbents to social (including economic and political) rewards (Treiman). In this way occupational incumbency may be viewed as a proxy or index of social standing and occupational mobility as an index of social mobility. The terms "proxy" and "index" are used deliberately, for we would not wish to reify the concept of occupational status nor tc discourage the analysis of other aspects of social inequality.