Most prior work touching on the issue of locus has done so tangentially, rough measures of intra-industry dispersions in return being mentioned in passing within a study on a different topic. Stigler, for example, studying the convergence of profit rates over time, used the relative proportions of positive-profit and loss corporations to construct rough estimates of intra-industry variances in the rate of return by IRS size class (his estimates unavoidably confound inter-period and inter-firm variances). He remarked in passing (1963: 48) that these values were much larger than inter-industry variances, but drew no implications. Fisher and Hall (1969) measured the long-term (1950-1964) dispersion in rates of return about industry averages in order to obtain a measure of risk that could be regressed against industry profitability. Although they did not remark the fact, they obtained estimates that were approximately double their reported standard deviation in inter-industry rates of return.