The calculated value of the energy consumption rate UT within the near-Earth and middle magnetosphere depends significantly on the assumed loss time &tgr; of the ring current, which is known not to be a constant. In much previous work, &tgr; was taken to be a function of a combination of solar wind quantities (the &egr; parameter) assumed to represent the solar wind energy input into the magnetosphere. This may lead to problems of circular reasoning and artificial interdependence of quantities when the statistical relation between UT and &egr; is investigated. To avoid these problems, I propose that &tgr; be taken as a function not of &egr; but of UT itself. Values of UT independent of &egr; or any other similar solar wind quantity can then be obtained at a cost of only a modest increase of computational effort. ¿ American Geophysical Union 1987