Supplementaryexplanation about the methodology and questionnaire
In this paper, we have used the standard Analytical Hierarchy Process (AHP) questionnaireas the main tool of gathering information, and assessing the views of specialists and experts in our sample. To do so, we selected criteria and alternatives as explained in section 3. Then, the following steps have been taken in accordance with AHP algorithm:
1)In the first step, pairwise comparisons of criteria were made according to the following table, and priorities were derived to determine the preferred criterion. Furthermore, preference levels of each criterion were determined.
Table A. Pairwise comparisons of criteria (Please specify the preferred criterion and itspreference level.)
No. / Pairwise comparisons of criteria(Please select the preferred criterion) / Please specify the importance level of each criterion.
Equally importance / Moderate importance / Strong importance / Extreme importance / Extremely more important
1 / Cost of method / Water level
2 / Cost of method / Weather pollution and stench emission
3 / Cost of method / Separation of waste materials
4 / Cost of method / Soil type and emulsion penetrability
level in soil
5 / Soil type and emulsion penetrability level in soil / Water level
6 / Soil type and emulsion penetrability level in soil / Weather pollution and stench emission
7 / Soil type and emulsion penetrability level in soil / Separation of waste materials
8 / Water level / Weather pollution and stench emission
9 / Water level / Separation of waste materials
10 / Weather pollution and stench emission / Separation of waste materials
For example, if an expert believes that "Separation of waste materials" is preferred over "Cost of method" and its importance level is extreme, he/she should fill the table as follows:
No. / Pairwise comparisons of criteria(Please select the preferred criterion / Please specify the importance level of each criterion.
Equally importance / Moderate importance / Strong importance / Extreme importance / Extremely more important
Cost of method / Separation of waste materials /
After filling the mentioned table, verbal judgments converted to numerical judgments using table 1 in the paper. Then, we aggregated expert's views by geometric mean. After that, AHP technique steps have been taken to obtain the weights of criteria, as explained in section 5.1. (We can use Expert Choice software for increasing the speed and accuracy of calculations).
2)After obtaining the weights of criteria, we determined the importance levels of alternatives to derive the priorities. To do so, we analyzed pairwise comparisons of all alternatives in five separate tables (regarding the five criteria). The following table is one of the five tables and it shows pairwise comparisons of alternatives regarding"Cost of method".
Table B. pairwise comparisons of alternatives regarding "Cost of method". (Please specify the preferred alternative and its importance level)
No. / Please compare each couple of alternatives with regard to "Cost of method".(Specify the preferred alternative). / Please specify the importance level of each alternative
Equally importance / Moderate importance / Strong importance / Extreme importance / Extremely more important
1 / Recycling / Composting
2 / Recycling / Hygienic burial
3 / Recycling / Incineration
4 / Composting / Hygienic burial
5 / Composting / Incineration
6 / Hygienic burial / Incineration
Other four tables showpairwise comparisons of alternatives regarding the other four criteria.
When these five tables were completed,verbal judgments converted to numerical judgments, and expert's views were aggregated. After that, using AHP technique steps we derived the importance levels of each alternative by Expert Choicesoftware. Then, we extracted the final ranking of the alternatives.
For better understanding of the process and analyzing the questionnaire, it would be helpful to note the following issues:
- In order to better understanding of different aspects of considered criteria and alternatives, some basic explanations about them (including definitions, concepts, the way of implement, advantages, and disadvantages) provided in the beginning of the questionnaire.
- All questionnaires filled out in front of authors and some complementary explanations provided to respondents as needed.
- To ensure the reliability of the comparisons and consistency of the method, we calculated consistency ratios of all tables of pairwise comparisons according to section 5.1.3. After confirmationof the consistency ofcomparisons, we began to analyze the questionnaires. In this research,six questionnaires were eliminated because they didn't fill out correctly or their consistency ratioswere more than 0.1.
- Statistical society of the research includes 48 specialists and experts of 12 organizations responsible for waste management of Mazandaran's cities. These experts are familiar with our considered alternatives, criteria, and related concepts.
- We have provided detailed explanations on methodology and methods used in the manuscript in section 4 and 5. Selection of the techniques was done according to the literature and comments of province's professors who are familiar with theoretical models and the geographical location of the considered area. Some of the main reasons for choosing these techniques are provided in section 5. Furthermore, by choosing Fuzzy AHP technique we have tried to analyze decision making under uncertainty.
- In the process of using Fuzzy AHP technique, we convertedverbal judgments to numerical judgments using table 2 in the paper,and completed the stages of this technique as section 5.2.
- Criteria and alternatives of questionnaire have been selected using library studies and studying related internal and external articles, and finally these have been revised and confirmed by experts in order to ensure its content validity.