The Structural Model Of The ISM Methodology: Analysis Approach

3.2 ISM Methodology
ISM is a qualitative tool developed by Warfield in 1974 with the objective of understanding the mutual relationships among various issues related to a problem. ISM is a process that enables individuals or groups to develop a structural model of the contextual relationships among elements in any situation and it calculates binary matrix which is also called as adjacency matrix. (Huang et al. 2005). Its basic idea is to use expert’s opinion to decompose a complex system into several subsystems and to construct a multilevel structural model (Warfield 1974a, b; Lee and Lin 2011). The ISM methodology is called as interpretive because the expert opinion will decides whether and how the barriers are related. It is structural too,

In developing SSIM, following four symbols have been used to denote the direction of relationship between two barriers i and j.
V- Barrier i will influence barrier j;
A- Barrier j will influence barrier i;
X- Barrier i and j will influence each other;
O- Barrier i and j are unrelated
STEP 4: In this step, initial reachability matrix and final reachability matrix from the SSIM are to be developed. Thus, SSIM is needed to be transformed into binary digits; (i.e. 0s or1s) called initial reachability matrix. The SSIM has been converted into a binary matrix, by substituting V, A, X and O by 1 and 0 as per given case. The following rules for the substitution of 0s and 1s are as follows:
1. If the (i, j) entry in the SSIM is V, the (i, j) entry in the reachability matrix becomes 1 and the (j, i) entry becomes 0;
2. If the (i, j) entry in the SSIM is A, the (i, j) entry in the reachability matrix becomes 0 and the (j, i) entry becomes 1;
3. If the (i, j) entry in the SSIM is X, the (i, j) entry in the reachability matrix becomes 1 and the (j, i) entry also becomes 1;
4. If the (i, j) entry in the SSIM is O, the (i, j) entry in the reachability matrix becomes 0 and the (j, i) entry also becomes