Why no Pareto in EP23 is a problem

I have previously commented on deficiencies in CLSI’s risk management standard EP23. The word Pareto cannot be found in this document. Here’s why that’s a problem.

First, a Pareto chart or table is a means of ranking potential failure modes so that one can concentrate on the top failure modes. The ranking is facilitated by means of classifying the potential failure modes with respect to severity and probably of occurrence. The ranking is required because financial resources are limited.

In the example for EP23, 13 potential failure modes are considered for a hypothetical glucose assay. With only 13 potential failure modes, each one can thoroughly analyzed and mitigations proposed. There is no need for Pareto analysis. But in the real world, hundreds of potential failure modes can be enumerated for an assay. This does not mean that the example must contain every potential failure mode but without a Pareto analysis, one does not demonstrate the ranking required to focus resources on the most serious potential failures. Note that the ISO document on risk management 14197, while not using Pareto analysis, uses something which achieves the same purpose – the limited (only six) potential failures are put into a risk matrix, which graphs severity against probability of occurrence for each failure mode, allowing one to focus on the most important failures.

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