IS THERE EMPIRICAL EVIDENCE FOR DECREASING RETURNS TO SCALE IN A HEALTH CAPITAL MODEL?
估计了一个扩展的Grossman健康资本模型中的健康投资方程，检验健康生产函数是规模报酬不变还是递减，结果支持递减但工具变量估计不稳健。
We estimate a health investment equation, derived from a health capital model that is an extension of the well-known Grossman model. Of particular interest is whether the health production function has constant returns to scale, as in the standard Grossman model, or decreasing returns to scale, as in the Ehrlich-Chuma model and extensions thereof. The model with decreasing returns to scale has a number of theoretically and empirically desirable characteristics that the constant returns model does not have. Although our empirical equation does not point-identify the decreasing returns to scale curvature parameter, it does allow us to test for constant versus decreasing returns to scale. The results are suggestive of decreasing returns and in line with prior estimates from the literature. But when we attempt to control for the endogeneity of health by using instrumental variables, the results become inconclusive. This brings into question the robustness of prior estimates in this literature.