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Moderator variables: A clarification of conceptual, analytic, and psychometric issues

1982; Academic Press; Volume: 29; Issue: 2 Linguagem: Inglês

10.1016/0030-5073(82)90254-9

1878-2647

Hugh J. Arnold,

Sensory Analysis and Statistical Methods

A distinction is drawn between the degree of relationship between two variables X and Y and the form of the relationship between the same variables. The correlation coefficient rxy is the index of degree of relationship, while the regression coefficient Byx is the index of the form of relationship. If both the form and degree are constant across values of some third variable Z, the X − Y relationship is constant or unconditional with regard to Z. If the degree of relationship varies with values of Z, Z is said to “moderate the degree” of the X − Y relationship. If the form of relationship varies with values of Z, Z is said to “moderate the form” of the relationship. The separate statistical tests which are required to test for each type of moderator variable are outlined. Hierarchical multiple regression is the appropriate method to test for different forms of relationship, but not for different degrees of relationship. The differing substantive implications and interpretation of the two types of moderated relationships are discussed. Finally, the effects of unreliability of measures on the power of tests to detect differing forms and degrees of relationships are outlined and demonstrated.