Ranking the Priority for Attention

The defuzzification process creates a single assessment from the fuzzy conclusion set expressing how corrective actions can be prioritised. Several defuzzification techniques have been developed (Runkler and Glesner (1993)). One common technique is the weighted mean of maximum method (WMoM), which is illustrated here. This technique averages the points of maximum possibility of each fuzzy conclusion, weighted by their degrees of troth. 

Suppose the potential cause identified in the FMEA has the following probability of occurrence, severity and detectability Probability of Occurrence - Remote, Severity - Remote, and Detectability - Moderate. Referring to the role base that will be introduced in Table 7.11, the priority of attention is, for example. Low, 0.06 Fairly Low with a support value of 0.055 and 0.461, respectively. Using the WMoM method, the weighted mean, (Z), can be calculated as  

From this result the priority for attention of this particular event can be numerically expressed as being 0.078. This method of defuzzification has been discussed in Chapter 6. Similarly all the potential failure modes identified in the FMEA can be analysed in this manner to produce a ranking such that the highest value of the defuzzified conclusion reflects the highest priority for attention. 

---