Probability of Failure

After a Probabilistic analysis has been computed, the Probability of Failure is listed in the Legend in the 2D View, and in the Info Viewer. The Probability of Failure is specified as a number between 0 and 1, where 0 = zero Probability of Failure and 1 = 100 percent Probability of Failure.

The definition of Probability of Failure in RocTopple is:

PF = Number of Failed Slopes / Number of Samples

where:

Number of Failed Slopes = 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.