The first part of the Kepner Tregoe matrix is going through a normal Decision Matrix. Afterwards, the top 3 from this matrix is selected for analysis in the matrix shown just above.
Executing the Method

Do the Decision Matrix Technique
First, do the decision matrix technique for all alternatives.

Select Top 3
Select the top 3 scoring alternatives from the decisionmatrix.

List Adverse Effects
For each of these alternative, list the adverse effects (in a table as shown above).

Score Adverse Effects
Score each of these adverse effects based on their significance (for example with lowhigh or a 15 scale) and probability (the change the adverse effects happens).

Multiply and Enumerate
Scores can by multiplied by the probability and eventually be summed to form a total score.

Select Alternative
In general, the alternative with the least strong adverse effects in total can be considered the best alternative.