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|In PROMETHEE III method, an interval [xa,ya] is calculated using equation, xa=φ(a)-ασa and ya= φ(a)+ασa. What is α in these equations and how its value is decided?|
The idea behind PROMETHEE III was to detect proximities between net flow values, taking into account the variations in the pairwise comparisons (measured by sigma(a)).
In the PROMETHEE III implementation, the alpha parameter was adjusted in order to detect close proximities only and to obtain a preorder (with a transitive indifference relation). If alpha is too large, all actions will be indifferent because all the intervals will overlap. If alpha is too small, you obtain the PROMETHEE II ranking.
Practically, with the visual representations available in the newer PROMETHEE software, it is possible to directly appreciate the proximities between the flow values. That's the reason why PROMETHEE III is rarely used.
Last update: 02:59 AM Tuesday, March 20, 2012
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