Testing identifying assumptions in bivariate probit models

This paper considers the bivariate probit model's identifying assumptions: linear index specification, joint normality of errors, instrument exogeneity, and relevance. First, we develop sharp testable equalities that detect all possible observable violations of the assumptions. Second, we propose an easy-to-implement testing procedure for the model's validity using existing inference methods for intersection bounds. The test achieves correct empirical size and performs well in detecting violations of the conditions in simulations. Finally, we provide a road map on what to do when the bivariate probit model is rejected, including novel bounds for the average treatment effect that relax the normality assumption.     

The impacts of share pledging on firm investment timing and valuation

This paper applies a model in the real options framework to analyze the impacts of controlling shareholder’s share pledging on corporate investment timing and valuation. We find that the optimal investment timing shows an inverted U-shape with the pledge ratio, indicating that share pledging exacerbates firms’ over-investment and worsens firms’ under-investment. Furthermore, share pledging hurts firms’ option value unless active measures are taken to control the pledging risks. The maintenance requirement can keep controlling shareholder from irrational early investments and protect investors from severe wealth losses. In addition, our work can provide testable empirical implications.     

韩国四次国土规划的变迁、评价及其启示

在回顾韩国四次国土规划目标和内容变迁的基础上,剖析了韩国国土规划的基本特点和存在的缺陷,提出了韩国国土规划尤其是第四次国土规划对我国的启示和借鉴。