Design matrix analysis

Analysts of social mobility are coming round to the view that it is not enough to find a model that fits the data; it is at least as important to know which bits of the model fit the data, and which are unimportant. The need for this type ofstructuring becomes even more pressing when we seek to determine the dimensions along which societies differ. This paper carries the process of structuring a stage further by proposing an orthogonal decomposition of a mobility model in which each dimension (degree of freedom) can be given a distinct sociological interpretation.