Construct validity of some unweighted product-count diversification measures

Construct validities are assessed for three simple-to-compute, unweighted, SIC-based continuous diversification measures and a recently proposed two-dimensional, SIC-based categorical diversification measure. Two of the three continuous measures are found to correspond strongly to Rumelt's categorical measures, suggesting that these two objective and easy-to-calculate measures are better suited for large sample, strategy research than has previously been assumed. No support is found for the two-dimensional measure.