After reviewing materials for the Fukushima Daiichi anniversary round-up, I appreciated the recent comments of the UK’s Royal Statistical Society. It said that the public is “currently desperately ill-served by the lack of ready access to up-to-date balanced and trustworthy information on the possible risks associated with different energy sources” and adds that “those that exist appear to be either reassuring propaganda or are limited to a particular hazard”.

These issues particularly come up in two of the hardest aspects of Fukushima to really understand: unlikely natural events, and uncertainty.

For example, a key contention of the American Nuclear Society report is that neither TEPCO nor the Japanese regulator did its homework; a proper probabilistic risk analysis would have found that a 1000-year tsunami return rate is too great a risk. The conclusion is based on archaeological evidence suggesting that there have been three tsunami in the region over the past 3000 years.

I don’t know whether TEPCO or the regulator should have seen the tsunami coming. But I do know that you can’t use a sample of two or three to make a rule; it is simply not enough data to be reasonably certain of a pattern. The margin of error is not only huge, its size is unknown. (This is in fact TEPCO’s stated position.)

The Royal Statistical Society seems to back this up when it said that in risk communications, the UK government should “…provide a clear warning that the past does not necessarily predict the future, and that we should be wary of being either reassured or scared by historical events.”

Its comments were for a UK legislature (House of Commons) science and technology inquiry into risk perception and energy infrastructure in December 2011 (web site via The written evidence document includes comment from leading scientists, researchers and expert societies. The voices may be (mostly) British, but the same tune is sung around the world.

I believe that a deep understanding of randomness, and of very infrequent events, goes against human nature. Risks posed by infrequent natural events are even harder to understand; they reach the limits of human understanding.

The area between certainty and uncertainty is also tricky ground, but unfortunately must be dealt with in discussions of the risks of radiation, as Steve Kidd points out.

Uncertainty is misunderstood, said another group that gave Parliamentary evidence, Sense About Science. It says: “Uncertainty is typically taken to mean ‘we don’t know’, when rather it is a statement of how confident we are.” A popular guide to uncertainty is now in preparation to join others published on

One of the scariest things about Fukushima is that it brings to light how far removed most people are in their day-to-day lives from the science and engineering that actually makes things work. They don’t know, they don’t want to know, and if they do react, it’s bound to be emotional rather than rational, as Kidd argued last month.

The House evidence is an antidote to that kind of thinking. I particularly recommend the Royal Statistical Society’s 12 principles for numerical communication of risks associated with energy sources (p. 51). For example, it advises that communicators should: include both quantifiable risks and those that are important but difficult to quantify; be clear about uncertainty attached to numbers, which should only be given to the precision justified by the evidence; and acknowledge uncertainty and limits to the data and knowledge. More controversially, it also argues that communicators should ‘attempt to provide a balanced view that does not seek, or appear to seek, to persuade.’ These criteria seem to me an excellent way to judge the quality of statistical reasoning of pro- and anti-nuclear commentary in the future.

This article first appeared in the May 2012 issue of Nuclear Engineering International magazine

Author Info:

Will Dalrymple is editor of Nuclear Engineering International

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