In a Failure Modes and Effects Criticality Analysis (FMECA), the Criticality Index combines which factors to rank failure modes?

• A. Cost and time
• B. Detectability and cost
• C. Severity and probability (and often detection)
• D. Frequency and repair time

Answer: (C)

The main idea is that FMECA ranks failure modes using a risk index that blends how bad the effect would be with how likely the failure is to occur, and often how easy it is to detect before it causes harm. The best answer reflects that combination: severity of the potential impact, probability (occurrence) of the failure, and frequently a detection factor. Multiplying these (Severity × Occurrence × Detection) yields a single index used to prioritize which failure modes to address.

Cost or time aren’t part of this ranking metric, and while frequency relates to probability, the key point is tying the likelihood to the severity of impact, with detection added to distinguish between hard-to-detect and easily caught failures.