Dear Goran Petrovic , Jelena Mihajlovic , Danijel Markovic , Sarfaraz Hashemkhani Zolfani * and Miloš Madic

I have read you paper

Comparison of Aggregation Operators in the Group Decision-Making Process: A Real Case Study of Location Selection Problem

My comments

1- In page 4 you say “The application of fuzzy-based MCDM methods makes it possible to handle imprecision and uncertainty during the decision-making process”

This is true, provided that data has a certain level of credibility, but if they come from personal appreciations and invented weights, which is the purpose of using fuzzy?

2- In page 4 “Thus, group decision-making (GDM) is introduced. A GDM problem could be observed as a DM problem with multiple possible alternative solutions and a set of decision-makers/experts that evaluate alternative solutions to accomplish a common goal considering their opinions, preferences or judgments”

Of course, GDM is much better than a single DM, the question is: How do you consolidate the different opinions and suggestions, select some and choose other? And GDM is valid as long as each member of the GDM uses reasoning, not intuition; knowledge, no divination; common sense, not feelings.

“The tendency is to enhance the DM process by adopting different techniques”

And what is the gain of doing that? You get a series of rankings, and possible different, and even if they are similar, there is not guaranty that t hey are the best

3- Page 5 “The advantage of using aggregation operators, compared to other methods (Delphi method, brainstorming, majority voting, consensus, etc.), is their objective sublimation of different opinions of experts’

Yes, I can believe that, but their complexity bans them in practical applications; for instance, if you have to make many different hypothesis and changes as in common practice

4- “Fuzzy Analytic Hierarchy Process (F-AHP)”

Did you know that this process was rejected by Saaty, the creator of AHP?

5- Page 7 “The AHP method is the MCDM method which can be used for the analysis of complex decisions using mathematics and psychology”

I am afraid that I disagree. AHP cannot be used in a complex scenario, simply because most of them have many interrelationships between criteria, vertical, horizontal and in diagonal, like in a network, and that is something that the rigid lineal hierarchically structure of AHP, can not do. It is not my opinion; it is a fact. Why do you think that after AHP appearance, Saaty developed ANP, which can handle it?

6- On page 7” The F-AHP method can eliminate the shortcomings of the classical AHP method’

Could you justify this assertion? Again, it fuzzifies something that is already not only fuzzy, but invented.

You talk about several methods to determine weights. In my opinion they don’t do the job because they are subjective, and thus, another DM or DMG could get different results. I would recommend MEREC, a rational and exact method to determine weights importance, unless, of course, that you use objective weights like those from entropy or standard deviation. In these methods, WHOEVER makes the weighting, the result is always the same, but you cannot use fuzzy with them, and it is not needed either

7- I notice that you are considering an alternative per criterion. In my opinion, this is incorrect, because in so doing you are not taking into account the influence of one criterion over another. For instance, treating used motor oil is accomplished by distillation and refining, which are large installations. These means a heavy road traffic and potentially odors. It is obvious that most people don’t like to have this installation nearby, therefore, their degree of acceptance must be consulted, and this may vary according to the location, as well as connected with criterion C 8, population density.

I hope these comments can help

Nolberto Munier