Kugler, Jacek, and Marina Arbetman. “Choosing Among Measures of Power: A Review of the Empirical Record.” In Power in World Politics, edited by Richard J Stoll and Michael Don Ward. Boulder, Colo: L. Rienner Publishers, 1989.
"We show that, for major powers, a number of indicators used in international politics to index power are highly related. Whether one chooses to use GNP, the COW Indexes, or adjust these for military expenditures is not critically relevant for the analysis of relations among major powers over time. This choice affects cross-sectional analysis since rank varies at one point in time but even here the average disparity is on the order of 10%" (73-4).
