Why Are Concavity Conditions Not Satisfied in the Cost Function? The Case of Japanese Manufacturing Firms during the Bubble Period*
研究日本制造业企业在1980年代泡沫时期成本函数不满足凹性条件的原因，发现弱银企关系和大量土地交易是主因，并指出忽略这些企业会错误估计土地与其他投入的替代弹性。
This paper examines empirically the reasons why Japanese manufacturing firms frequently fail to satisfy concavity of the cost function in input prices. We focus on the ‘bubble period’ in the 1980s when land was in great demand and land prices soared. By estimating the translog cost function with land as one of production inputs, we find that violation of concavity mainly resulted from weak bank–firm relationship and massive transactions of land. We also demonstrate that elasticities of substitution between land and other inputs are estimated quite differently if the firms violating concavity are not excluded from the analysis.