To calculate the rank of an alternative, well-known approaches,
such as AHP and TOPSIS, can be applied. The main idea of AHP is to
cluster decision criteria by comparing them pair-wise. This independent comparison enables simple criteria sorting according to
human decision processing. Following this, all pair-wise comparisons
are converted to numerical values and an eigenvector can
be calculated to provide an overall and normalized weighting of
all criteria. In the next step all normalized total rating values for
each evaluation criterion are stored in a comparison matrix. This
comparison matrix is multiplied by the eigenvector to determine
the final ranking of all alternatives. AHP is integrated into the decision-
support system. Ranking lists for alternatives in TOPSIS are
calculated based on the distance from an alternative to pre-calculated
positive-ideal and negative-ideal solutions. The calculations
of ideal and negative-ideal solutions require a classification into
benefit and deficit criteria. Depending on this classification, TOPSIS
results can vary widely. TOPSIS cannot be applied if an exact classification
of a certain criterion is not possible. Criteria weights are
not calculated by the TOPSIS approach and have to be adopted
from other approaches. The pair-wise comparison from AHP leads
to suitable results and is therefore used.