Archives For Communication


With much pomp and circumstance the attorney general and our top state security mandarin’s have rolled out the brand new threat level advisory system. Congrats to us, we are now the proud owners of a five runged ladder of terror. There’s just one small teeny tiny insignificant problem, it just doesn’t work. Yep that’s right, as a tool for communicating it’s completely void of meaning, useless in fact, a hopelessly vacuous piece of security theatre.

You see the levels of this scale are based on likelihood. But whoever designed the scale forgot to include over what duration they were estimating the likelihood. And without that duration it’s just a meaningless list of words. 

Here’s how likelihood works. Say you ask me whether it’s likely to rain tomorrow, I say ‘unlikely’, now ask me whether it will rain in the next week, well that’s a bit more likely isn’t it? OK, so next you ask me whether it’ll rain in the next year? Well unless you live in Alice Springs the answer is going to be even more likely, maybe almost certain isn’t it? So you can see that the duration we’re thinking of affects the likelihood we come up with because it’s a cumulative measure. 

Now ask me whether a terrorist threat was going to happen tomorrow? I’d probably say it was so unlikely that it was, ‘Not expected’. But if you asked me whether one might occur in the next year I’d say (as we’re accumulating exposure) it’d be more likely, maybe even ‘Probable’ while if the question was asked about a decade of exposure I’d almost certainly say it was,  ‘Certain’. So you see how a scale without a duration means absolutely nothing, in fact it’s much worse than nothing, it actually causes misunderstanding because I may be thinking in threats across the next year, while you may be thinking about threats occurring in the next month. So it actually communicates negative information.

And this took years of consideration according to the Attorney General, man we are governed by second raters. Puts head in hands. 

Icicles on the launch tower (Image source: NASA)

An uneasy truth about the Challenger disaster

The story of Challenger in the public imagination could be summed up as ”’heroic’ engineers versus ’wicked’ managers”, which is a powerful myth but unfortunately just a myth. In reality? Well the reality is more complex and the causes of the decision to launch rest in part upon the failure of the participating engineers in the launch decision to clearly communicate the risks involved. Yes that’s right, the engineers screwed up in the first instance. Continue Reading…


Why risk communication is tricky…

An interesting post by Ross Anderson on the problems of risk communication, in the wake of the savage storm that the UK has just experienced. Doubly interesting to compare the UK’s disaster communication during this storm to that of the NSW governments during our recent bushfires.

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While I’m on the subject of visualising risk the Understanding Uncertainty site run by the University of Cambridge’s Winton Group gives some good examples of how visualisation techniques can present risk.

Matrix (Image source: The Matrix film)

Just updated my post on Decision Theory and the Risk Matrix with some material on the semiotics of colour and the advantages, as well as disadvantages, that it’s use in constructing a risk matrix brings.

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.

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For the STS 134 mission NASA has estimated a 1 in 90 chance of loss of vehicle and crew (LOCV) based on a Probabilistic Risk Assessment (PRA). But should we believe this number?

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