Cortese C F, Leftwich J E
Demography. 1975 May;12(2):325-9.
An assessment of the occupational opportunities for selected groups of in-migrants (i.e., Negroes) requires a technique which controls for effects of both national and local employment patterns. We suggest a measure based upon the location quotient and referred to as the "differential opportunity ratio" as a method which provides the necessary controls. It is applicable in the comparative studies of cities and in analyses of other population groups for which data are available.
对特定移民群体（即黑人）的职业机会进行评估，需要一种能够控制国家和地方就业模式影响的技术。我们建议采用一种基于区位商的度量方法，称为“差异机会比率”，作为一种能提供必要控制的方法。它适用于城市的比较研究以及对有数据可用的其他人口群体的分析。
