Fault tree analysis identifies causes of a major undesirable event (fault) in a system. Adapted from engineering, it is a technique frequently used in needs assessment. Not passing a certification examination is an example of an undesirable event that would be placed at the top of a tree. Key factors possibly causing that event would be situated under the top, followed by subfactors causing the key factors, and so forth, thus forming a tree-like figure. Key factors could be grouped into those under the control of the system and those not. Failure pathways can be ascertained through quantitative and qualitative procedures.