Archives For Heuristics

Matrix (Image source: The Matrix film)

Why the risk matrix?

For new systems we generally do not have statistical data on accidents, and high consequence events are, we hope, quite rare leaving us with a paucity of information. So we usually end up basing any risk assessment upon low base rate data, and having to fall back upon some form of subjective (and qualitative) method of risk assessment.

Risk matrices were developed to guide such qualitative risk assessments and decision making, and the form of these matrices is based on a mix of decision and classical risk theory. The matrix is widely described in safety and risk literature and has become one of the less questioned staples of risk management.

Despite this there are plenty of poorly constructed and ill thought out risk matrices out there, in both the literature and standards, and many users remain unaware of the degree of epistemic uncertainty that the use of a risk matrix introduces. So this post attempts to establish some basic principles of construction as an aid to improving the state of practice and understanding.

Continue Reading…

Disappointingly the Black Saturday royal commission report makes no mention of the effect of cognitive biases upon making a ‘stay or go’ decision, instead assuming that such decisions are made in a completely rationa fashion. As Black Saturday and other disasters show this is rarely the case.

Continue Reading...

From the BEA’s second interim report (BEA 2009) we now know that AF 447 was flown into the water in a deep stall. Given the training and experience of the flight crew how did they end up in such a situation?

Continue Reading...