A COMPARISON OF VARIOUS INDEXES OF DIFFERENTIATION FOR HOLLAND MODEL

Five indices of differentiation for Holland's model were compared for two sets of data. Iachan's indices were most similar to each other and to the Spokane and Walsh index. It was suggested that, in general, Iachan's indices should be used as measures of differentiation. However, if differentiation within the three-letter summary code is of interest, then the Spokane and Walsh index (difference between the first and the third highest scores) would be more appropriate. In terms of the criterion of relationship with career decision, none of the indices proved to be better. Alternative explanations are offered for the lack of relationship between differentiation and career decision. © 1990.