In Failure Modes and Effects Analysis, Paul Palady describes how detection is reactive and explains that failures modes should be prioritized based only on severity and occurrence, which are proactive. To assess criticality, Palady recommends plotting the severity and occurrence values of all failure mode effects on an area chart and then dividing this chart into three regions of risk: high, medium and low.

Failure modes are then assigned a risk level based on where they appear on the area chart. Failure modes plotted above the high risk line are tagged as high risk, failure modes between the lines are tagged as medium risk, and failure modes below the low risk line are tagged as low risk.