Probability of Failure

After a Probabilistic analysis has been computed, the Probability of Failure is listed in the Pillar Information panel of the Sidebar display, and in the Info Viewer.

The Probability of Failure is specified as either:

• A fraction between 0 and 1, where 0 = zero probability of failure and 1 = 100 percent probability of failure; or
• A percentage between 0 to 100% probability of failure.

The definition of Probability of Failure in CPillar is:

PF = Number of Failed Pillars / Number of Samples

where:

• Number of Failed Pillars = number of analyses with Factor of Safety < 1
• Number of Samples = Number of Samples specified in the Project Settings dialog

Example

If the Number of Samples = 1000 and the number of analyses with factor of safety < 1 = 150, then the Probability of Failure = 150 / 1000 = 0.15 or 15 percent.