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Prioritization of biofuels production pathways under uncertainties  343



              Definition 6 The possibility of an interval being greater than another
                                                     +             +

                                                      Š and y¼[y ,y ], the possi-
              For two arbitrary interval numbers x ¼ x , x½
              bilities that x y and that b a are defined in the following two equations,
              respectively (Xu and Da, 2003):
                                                             +
                                                            y  x
                           +        +

                            Š   y , y ŠÞ ¼ max 1  max                    ,0
                                                        y  y + x  x
               p xy ¼ px , x½ð  ½                        +        +

                                                                         (12.7)
              2.2 Interval AHP
              The interval analytic hierarchy process (IAHP) developed by Xu and Da
              (2003) has been widely used in various fields for its advantage of address
              ambiguity and hesitation existing in human judgments. Ren (2018) summa-
              rized the IAHP method developed by Xu and Da (2003) in the following
              three steps:
                 Step 1: Establishing the interval pair-wise comparison matrix.
                 Assuming that there are n criteria (C 1 ,C 2 , …,C n ) which need the
              stakeholders/decision-makers to determine the relative importance
              (weights), the stakeholders/decision-makers were asked to use the Saaty’s
              nine-scale system (Saaty, 2008) to establish the pair-wise comparison matrix
              (see Table 12.1). However, it is different from the traditional AHP method
              which relies on employing the numbers(from 1 to 9) and their correspond-
              ing reciprocals to establish the pair-wise comparison matrix, the users of the
              interval numbers rather than the single numbers which sometime cannot

              Table 12.1 Saaty scales for establishing the pair-wise comparison matrix (Saaty, 2008)
              Scales  Definition     Explanation
              1       Equal          Two elements perform equally
                        importance
              3       Moderate       Experience and judgment slightly favor one element
                        importance     over another
              5       Essential      Experience and judgment strongly favor one
                        importance     element over another
              7       Very strong    An element is favored very strongly over another; its
                        importance     dominance demonstrated in practice
              9       Absolute       The evidence favoring one element over another is
                        importance     of the highest possible order of affirmation
              2,4,6,8  Intermediate  Intermediate value
                        value
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