The measure of income mobility in vector space

In this paper the income vector space is employed as a unified setting to analyze income mobility. The income mobility can be characterized by a change of the income vector during a given period: the norm of two income vectors can be formulated as a mobility index, which is found to be more generalized than those previous indexes; the angle between them indicates the structural change in income vector. Accordingly, the income mobility can be decomposed into a shift in the angle and a change in the norm.