Smooth Adjustment Hypothesis: A Case Study for Iranian Manufacturing Industries

Recent literature of intra-industry trade has paid attention to the relationship between intra-industry trade and adjustment costs. Adjustment costs include the losses due to temporary unemployment in the labor market, which arise from wage rigidity, the research costs, re-location and re-training of labor. Based on smooth adjustment hypothesis, intra-industry trade has a lower adjustment cost than inter-industry one. The present study has examined the smooth adjustment hypothesis for Iranian manufacturing industries at the 4-digit level of ISIC classification by using panel data during time period 2002-2006. For this, intra industry trade has been divided into its types (vertical and horizontal intra-industry trade) and then the hypothesis which is horizontal intra industry trade has lower adjustment cost than vertical one has been tested. Based on the results, the smooth adjustment hypothesis is not verified for Iran while employing total intra industry trade. But by distinguishing intra-industry trade to its types, the hypothesis is confirmed for horizontal intra industry trade. Also, the hypothesis which asserts that horizontal intra industry trade has low adjustment costs compared to the vertical one is verified. Based on the findings, it is suggested to pay more attention to intra-industry trade especially the horizontal one in promoting the foreign trade.