Description
Hi
I saw you've listed TODIM as one of your TO-Dos in README.md. I'm willing to implement it. However, I have some ambiguities in some steps of it. The method has originated through this study: https://www.academia.edu/download/56873871/1991_TODIM_Basic_and_application....pdf
My ambiguities are as follows:
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They claim that a score of 0-9 can be assigned to each alternative with respect to criteria. However, they should have mentioned how they chose the scores. For example, how did they figure out (or assign) a score of 1 to
$i'th$ alternative in the$c'th$ criteria? -
I'm confused about how did they finally find the weight of each criterion since they mentioned two approaches:
the scale from 1 to 9 is employed for relative comparisons between criteria. The use of this 1—9 scale relies on the latest formulation of the AHP method [17, 18].
[17] Saaty T.L., Multicriteria Decision Making, The Analytic Hierarchy Process, Thomas Saaty (ed), 1988.And in a bit further, they mentioned:
the weights of criteria are computed by averaging over the normalized columns.
As far as I know, In the AHP, the importance of each criterion is entered by the user, and the relative importance matrix over the set of given criteria is calculated:
julia> foo = [1, 2, 3] 3-element Vector{Int64}: 1 2 3 # the following is the pairwise comparison of criteria julia> compar = foo./[foo foo foo]' 3×3 Matrix{Float64}: 1.0 0.5 0.333333 2.0 1.0 0.666667 3.0 1.5 1.0
Afterward, the importance weights of the criteria (which tells how much each criterion will factor into the decision) are calculated using Geometric Mean:
julia> imp_weights = reduce(*, compar, dims=2).^(-1/length(foo)) 3×1 Matrix{Float64}: 1.8171205928321397 0.9085602964160698 0.6057068642773799
Finally, the weight of each criterion can be calculated using the following equation:
$W_c=\frac{imp\textunderscore weights_c}{\sum_{j=1} {imp\textunderscore weights}_j}$
where$c$ is the$c'th$ criterion,$imp\textunderscore weights_c$ is the importance weights of the$c'th$ criterionjulia> weights = imp_weights./sum(imp_weights) 3×1 Matrix{Float64}: 0.5454545454545454 0.2727272727272727 0.1818181818181818
But in this process, we do not have an operation like "averaging over normalized weights". So a clarification about whether they achieved the weight of criteria using the same approach in the AHP is needed.
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The last ambiguity is where they used a parameter named
$a_{rc}$ in determining the dominance of the$i'th$ alternative over the$j'th$ alternative:
$\delta_{(i, j)}=\sum [a_{rc}(w_{ic} - w_{jc})]$
They didn't mention what's$a$ in the above (or maybe I haven't grasped it). But I guess it should be the relative importance of the reference criterion over the$c'th$ criterion.