This paper contains a proof that under one testable condition a measure of economic mobility formed by the ratio of permanent to total variance employing the methods of Gottschalk and Moffitt (1994) is equivalent to the Shorrocks R constructed with a Theil General Entropy Index.

This article provides finite sample conditions for the ratio of permanent to total inequality based on methods of Gottschalk and Moffitt (1994) to be equivalent to the Shorrocks <italic>R</italic> constructed with a Theil General Entropy Index. A simple test emerges of whether the two measures can be seen as...