Step 1.

• A.

  Construct a pairwise comparison matrix (n × n) for criteria with respect to objective by using Saaty's 1–9 scale of pairwise comparisons as shown in Table 1. In other words, it is used to compare each criterion with each other criterion, one-by-one.

• B.

  For each comparison, we will decide which of the two criteria is most important, and then assign a score to show how much more important it is.

• C.

  Compute each element of the comparison matrix by its column total and calculate the priority vector by finding the row averages.

• D.

  Weighted sum matrix is found by multiplying the pairwise comparison matrix and priority vector.

• E.

  Dividing all the elements of the weighted sum matrix by their respective priority vector elements.

• F.

  Compute the average of this value to obtain λ_max.

• G.
  Find the consistency index, CI, as follows (Equation (4)):

  

  (4)

  where n is the matrix size.
• H.
  Calculate the consistency ratio, CR, as follows (Equation (5)):

  

  (5)
• I.

  Judgment consistency can be checked by taking the consistency ratio (CR) of the CI with the appropriate value as shown in Table 2. The CR is acceptable, if it does not exceed 0.10. If it is more, the judgment matrix is inconsistent. To obtain a consistent matrix, judgments should be reviewed and improved.