The Basic Principles of research design of comparative research Morris Zelditch(197)) specifies that the design of comparative research is conditioned largely by four rules Comparability: Two or more instances of a phenomenon may be compared if and only if there exists some variable, say V, common to each instance J.S. Mill's 1st Canon Method of agreement: No second variable, say U, is the cause or effect of v, if it is not found when v is found. J.S. Mill's 2nd Canon(Method of Difference No second variables v is the cause or effect ofy if it is found when v is notThe Basic Principles of Research Design of Comparative Research Morris Zelditch (1971) specifies that the design of comparative research is conditioned largely by four rules: Comparability : Two or more instances of a phenomenon may be compared if and only if there exists some variable, say V, common to each instance. J.S. Mill's 1st Canon (Method of Agreement) : No second variable, say U, is the cause or effect of V, if it is not found when V is found. J.S. Mill's 2nd Canon (Method of Difference): No second variables U is the cause or effect of V if it is found when V is not