The Elasticity of Substitution Revisited: The Effects of Secular Changes in Labor Force Structure
指出，由于蓝领和白领劳动力的相对数量与价格随时间大幅变化，将劳动力加总为单一生产要素会扭曲资本与劳动替代弹性的估计，并证明传统调整方法可能加剧问题，实际替代弹性约为2.5。
Because the relative quantities and prices of blue- and white-collar labor have changed dramatically over time, aggregation into a single factor of production distorts estimates of the substitutability between capital and labor. This distortion is a function of growth rates of human and nonhuman capital and the rate of shift of the labor force from blue- to white-collar occupations. Conventional methods of adjusting for labor quality may actually increase the problem. Previous estimates of unity or less for the elasticity of substitution between capital and aggregate labor are shown to be consistent with a production function with a constant elasticity of substitution of about 2.5.