解析勞動儲藏與勞動報酬短期遞增的關係

Labor Hoarding, Dynamic Adjustment and Returns to Labor

過去在相關文獻中，勞動報酬的短期遞增是一極重要的實證發現。該種現象是指，在短期時勞動的需求產出彈性，亦即每百分之一的產量變動造成勞動需求的百分比變動，會小於一，而在長期時，勞動需求產出彈性會較短期的值來得大。勞動報酬短期遞增的發現很明顯的與傳統的廠商理論相矛盾，文獻中曾有些學者嚐試提供一些解釋，其中最著名的是Solow(1968)所提出的勞動儲藏理論。Solow以迅速調整勞動僱用所產生的調整成本來說明勞動儲藏的理性行為，並由此解釋勞動報酬的短期遞增現象。Solow之後，Morrison and Berndt(1981)嚐試以傳統變分法來解析勞動儲藏與短期勞動報酬遞增的關係。由於尤拉方程式求解的困難，Morrison and Berndt的模型必須對生產技術做極大的限制，因此，本研究以動態對偶模型來探討勞動儲藏與勞動報酬短期遞增之間的關係。在廠商追求跨期成本現值總和極小的行為假設下，藉著將產出成長分解的結果，我們證明勞動儲藏既非勞動報酬短期遞增的充分條件亦非必要條件。這個結果說明在調整成本的模型中，勞動報酬的短期遞增既非一種矛盾亦非如Solow所言為勞動儲藏的必然結果，因此，勞動報酬的短期遞增純粹是一個實證的議題。

Literature on the short-run relationship between output and employment has focused on the empirical phenomenon called 'short-run increasing returns to labor' (SRIRL). SRIRL signifies the phenomenon that fluctuations in output induce a variation of labor input less than proportional. The empirical finding of SRIRL represents a clear contradiction to the traditional theory of firm. There have been attempts to resolve this paradox, one of the general explanations offered involved the concept of labor hoarding. This research attempts to examine the role of labor hoarding in SRIRL by applying a dynamic dual model of explicit cost minimization. As an alternative approach to resolving the SRIRL paradox, the dynamic dual model offers greater flexibility in the specification of production technology. The results suggest that SRIRL does not necessarily contradict intertemporal optimization behavior and labor hoarding is neither sufficient nor necessary for SRIRL.