In decision theory, the weighted sum model (WSM) is the best known and simplest multicriteria decision analysis and multicriteria decision making method for evaluating a number of alternatives in terms of a number of decision criteria.
For a example suppose that a decision problem of this type is defined on three alternatives A1, A2, A3 each described in terms of four criteria C1, C2, C3 and C4.
For instance, assuming we input that the relative weight of the first criterion is equal to 0.20, the relative weight for the second criterion is 0.15, the third 0.40, the fourth 0.25. 

When the formula is applied on these numerical data the scores for the four alternatives are:
A1 = 25 x 0.20 + 20 x 0.15 + 15 x 0.40 + 30 x 0.25 = 21.50
...and assuming the results for the other alternatives are A2 = 22.00; A3 = 20.00; A4 = 21.00.
Then, the best alternative is alternative A2 (because it has the maximum WSM score which is equal to 22.00). The score results of each alternative determine the resulting rank order of alternatives:
 A2 > A1
 A1 > A4
 A4 > A3.


The software is designed to enable you to model common decision making problems using the weighted criteria (weighted sum model).
The software allows you to:
 maintain a journal of decision cases
 define the decision problem space
 select decision model
 model decision processes for single or multiple decision participants
 define decision criteria
 weigh decision criteria
 explore alternatives
 analyze alternatives
 score and rank alternatives
 report results

