A Study on the Efficiency of Companies Listed on the Tehran Stock Exchange Using Data Envelopment Analysis

In this research, we investigate the efficiency of companies listed on Tehran stock exchange using Data envelopment analysis (DEA). To do so, we compute the relative efficiency of the companies using input oriented CCR, BCC and CRS and VRS approaches and separate their inefficiency into two technical and scale sections. In continuous, we tend to determine the companies with the absolute efficiency among the companies with one hundred percent relative efficiency. Finally, we try to determine the reference groups as a pattern for improving their efficiency by identifying the weakly efficient companies. The research data were collected from financial statement of 75 companies listed in three different industries including chemical, food and non-metal in the Tehran stock exchange from 2006 to 2010. By considering the previous researches, in order to compute the efficiency of the companies, we use from two input variables including total assets and total liability to total assets ratio and three output variables including EPS, ROA and ROE. The results show that the significant amount of existing inefficiency is because of the scale inefficiency in these companies, while all the efficient companies in these three industries are as the weakly efficiency type and there isn’t any company with the absolute efficiency among them.