Mehrdad Nabahat - Sama Technical and Vocational Training College Islamic Azad University, Urmia branch, Urmia, Iran

Sometimes in the real world we are faced with the data occupying on interval for which providing the exact value for them is hard and complicated. Therefore, when we want to rank such data we need to use advanced decision making methods. In the conventional decision making, the developed TOPSIS method for interval data as one of the classical methods of multiple criteria decision making is important. In this paper we are going to concentrate both on ranking and selecting appropriate suppliers for cooperation in supplying parts of Tabriz Tractor Manufacturing Company based on interval data in order to avoid unnecessary expenses which are usually incurred for the company.Important criteria for the evaluation and ranking of suppliers of Tractor Manufacturing Company determined by library research and interviews with experts. Since there are different parts to be evaluated we consider only the ranking Casting parts manufacturer companies

Multiple criteria decision making (MCDM), Ranking, Interval TOPSIS method, Interval Data