L3; Pairwise Comparison Methods Flashcards
AHP
Analytical Hierarchy Process was proposed as a method to solve decision problems using a hierarchical structure of criteria and alternatives.
It has become one of the most popular decision-making methods due to the use of pairwise comparisons to input qualitative information.
Pairwise Comparisons
In Pairwise Comparisons, each alternative is compared one-on-one with each ot the other alternatives.
criteria weights can also be evaluated using pairwise comparisons.
AHP Limitations (4)
1.AHP Scale
the scale shows an over and under emphasis of the following criteria weights. Sometimes the score is exaggerated.
balanced scales is highly proposed.
Saaty suggests a relationship with equal dispersion between the scale values.
the difference in selelcting between the scale 1 and 2 is 15 times greater than the difference between 8 and 9.
2.Pairwise Consistency
decision-maker can be inconsistent.
using of a consistency index/ratio can help this problem
- Rank Reversal
Rank reversal occurs when an alternative is added or removed from the decision model after preferences have been provided. the updata can alter the results and sometimes reversing the order of preferences.It occurs due to interdependencies within the calculations. Supermatrix (Analytical Network Process) can overcome rank reversal in AHP.
it uses a network structure of criteria and alternatives rather than a hierarchical structure. According to Salo, ANP does not eliminate rank reversals and the most sensible approach to ensure rank reversals do not occur is by ensuring the alternatives and criteria are correct before data entry. This can be achieved by focusing on the problem structuring phase of the decision making process.
4.Time consumption
AHP requires 1/2n (n-1) comparisons.
Therefore if you have more than 3 criteria alternatives the decision-maker needs to input more information than a direct input method.
AHP Eigenvector function
geometric function
=MMULT(range, range)
=GEOMEAN(range,range)
