The need to compare factor score estimates across groups differing in age and culture, for example, can be met whenever some variables, factored in all the groups to be compared, are identical.Within the ordinary factor analytic procedures, anequipotentmethod is described, which throws scores from different groups into a combined standard score distribution, and operates on the scores of each group with its own factor estimation weights, but with the matrices for all the groups brought to equipotency.A more satisfactoryisopodicprocedure is also proposed, using covariance factoring, after first reducing artificial metric differences among variables by ‘universe standardizing’ conversions. But a more radical attainment of the isopodic goat is reached if the mean standardized covariance matrix is applied to the raw score deviations of members of all groups, brought into a combined distribution on each varia