Measuring the efficiency of forest harvesting companies with undesirable outputs using data envelopment analysis (Case study: Guilan providence)

The purpose of this study was to measure the relative efficiency of forest harvesting processing companies in Guilan province by considering pollution as an undesirable output. For this purpose, data envelopment analysis (DEA) method was used to evaluate the efficiency. In order to conduct this research, data from 12 forest harvesting companies in Guilan province were collected during 10-year period (2007-2016). First, the variable reduction method was used to reduce the indicators and then the units were ranked using the super-efficiency method. The results show that due to the importance of undesirable output, a number of companies have good ranks in terms of efficiency despite their high adverse undesirable output (air pollution) are in a good position in terms of efficiency (Iran Wood Coating Company and Layl Forest Cooperative). Due to the existence of undesirable output (air pollution) in forest exploitation companies, it is possible to improve the performance of companies with high efficiency along with undesirable output by reducing the amount of pollution.