TOPSIS (Technique for Order Performance by Similarity to Ideal Solution) is a very practical decision support method used in several areas
of life. This method already exists in the literature in the context of a single decision maker. In order to adapt this method to group decision
making, which can be easily applied in various situations, this work extended the TOPSIS method to group decision making using the
quadratic mean and the geometric mean. In this work, numerical applications have been made and interesting results have been obtained.

Group decision; extension-TOPSIS; geometric mean; quadratic mean