Abstract
Concern in this paper is with the specification of control procedures ensuring factor compatibility in spatiotemporal factorial ecology study. Specific attention is given to three considerations when factor solutions are to be used in the analysis of change: Parsimony, invariance, and homogeneity. A series of test procedures are proposed to determine the degree of factor compatibility between comparative solutions and to provide objective measures of parsimony, factor invariance, and variable homogeneity.