Investment in Fixed Capital Stock: Testing for the Impact of Sectoral and Systemic Uncertainty*
利用动态异质面板估计方法，检验部门不确定性（产出波动）和系统性不确定性（政治不稳定）对中等收入国家投资支出的负面影响，并发现物质资本与技能型人力资本存在互补效应。
Abstract This paper applies current theory recognizing the irreversibility of investment, in order to test for the impact of uncertainty on investment expenditure for a middle income country. The contribution of the paper is unique in two respects. First, it employs dynamic heterogeneous panel estimation techniques not previously applied to investment functions. Secondly, it explicitly tests for the impact of both sectoral and systemic uncertainty on investment expenditure. We find that both sectoral (as measured by output volatility) and systemic uncertainty (as measured by political instability) have a negative impact on investment rates in a middle income country context. Liquidity constraints and growth in total factor productivity are found to have no impact on investment, while trade liberalization has the impact predicted by Heckscher‐Ohlin trade theory. Finally, we find complementarity effects between physical capital and skilled human capital, suggesting that South African educational policies may have hampered investment in physical capital as well as the growth performance of the economy. Policy implications emphasize the importance of lowering uncertainty for investors, and the need for sound human capital investment.