A derivative of the chi-square statistic which provides a surface description of mobility patterns in a social mobility table. The coefficient describes immobility and mobility (association and dissociation) between origin and destination classes, relative to the limits imposed by the (changing) size of the classes over time, and so provides a summary descriptive measure of mobility between generations that adjusts for changes in the occupational structure. It takes a value in the range plus one (mobility greater than that expected from marginal effects alone) to minus one (mobility less than that expected from marginal effects alone). Values of zero represent an almost random pattern of mobility.
The Benini statistic is one of a number of measures of association in mobility tables which attempt to make a gross distinction between mobility brought about by changes in the occupational structure and mobility due to other factors (further examples include the index of association, disparity ratios, and odds ratios). These statistics all lack the advantage of the newer techniques of log-linear modelling; namely, that the latter permit one to test alternative models of mobility, in order to examine their respective criteria of fit.