Sustainability 2022 , 14 , 2619
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agriculture [47]. Ishizaka and Labib [49] reviewed the methodological developments of AHP and discussed some of the method’s advantages and disadvantages. 2.4.1. Development of the Hierarchy: Identification of Alternatives, Criteria and Sub-Criteria AHP was performed to choose the most appropriate approach from a practitioner’s individual viewpoint that could be taken to allocate the environmental impacts and costs of a biorefinery production process to two selected byproducts (goal). The most commonly applied allocation methods (alternatives) and their most prominent features were identified in a review of scientific papers on allocation issues. These features were summarized to form a smaller set of criteria and subcriteria for the sake of clarity and to reduce the risk of inconsistent answers. Thereafter, the hierarchy was derived, and this process is further described and illustrated in the Results section (Figure 3).
Figure 3. Structure and explanation of the AHP hierarchy, including the goal, criteria, subcriteria and alternatives. 2.4.2. Execution of the AHP In this study, the rating scale shown in Table 1 was used, and the relative weights, consistency ratios (a measure for the consistency of the given pairwise ratings within a matrix) and final priorities were calculated as described by Saaty [50]. As a rule of thumb, Saaty (1987) stated that if the “consistency ratio exceeds 0.10 appreciably, the judgments often need reexamination” (Saaty 1987, p. 165). However, in practical fields such as managerial research, a consistency ratio (C.R.) lower than 0.2 can be considered as tolerable [51]; therefore, when a single judgment had a C.R. lower than 0.2, it was tolerated. Matrices with a higher consistency ratio were either excluded (criteria and subcriteria rankings by the interviewees) or the weighting was repeated (rankings of alternatives). The pairwise comparisons of the alternatives regarding the (sub-)criteria were drawn with reference to the scientific literature on allocation, as described in detail in the Results section. For the weighting of (sub-)criteria, experts were selected (s.f. Section 2.4.3). As the focus of this study was placed primarily on comparing the different practitioners’ preferences regarding the (sub-)criteria rankings and the potentially different outcomes resulting from
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