Risk, Uncertainty and Everything Else

To follow up on my previous post regarding the work of Peter Sandman, I can’t help but advertise his short, yet important article entitled “Risk Words You Can’t Use” published in the August 2005 issue of The Synergist.  While this article is a quick read, I will distill it down further and caveat some with my personal experience:

• Conservative: To risk people, conservative means an overestimate of risk.  To laypeople, a “conservative” estimate is a low estimate.  So whereas a risk person would use conservative to overstate the risk, a layperson (or perhaps decision maker) may interpret the message to be an understatement of risk, and thereby think that the risk could be much worse.  Now, engineers and scientists understand what is meant by the word “conservative,” as in my “conservative analysis still shows the structure will not fail.”  And fortunately for me, when I described my idea of conservative discounting of expert opinions (to be explained in a later post that I will link to when it is available) I was speaking to an audience of security engineers.  I will keep Sandman’s advice to not use the word conservative when speaking to non-technical audiences, and instead opt for the word “overestimate.”
• Significant/Insignificant:To risk people and statisticians, a significant finding is one that is non-random.  To laypeople, whether an issue is significant depends on their emotions and value structure.  So, to tell people that the terrorism risk is insignificant might not communicate well.  It is true (right now based on our current understanding and situation) that a person’s individual risk to terrorism is very, VERY low, but the outrage is high, and thus the public’s emotional response might label terrorism as a significant threat.
• Positive/Negative: To risk people, a positive relationship means that when one variable goes up, so does the other.  To laypeople, a “positive” relationship is favorable from the point of view of risk.  The same can be said of negative relationships.
• Bias: Bias to a risk person means non random.  Bias to a layperson spells deceit.
• Anecdotal: Anecdotal evidence to a risk person means the evidence is just one sample from a much larger sample space.  Anecdotal to a layperson suggests the evidence is an amusing story.  This word might not bode well when talking about anecdotal evidence on poor public response following a catastrophic event.
• Risk [my personal favorite]: To risk people, the risk associated with a situation describes its probability and the corresponding consequences.  To laypeople, risk usually refers only to the probability component.  In fact, when lecturing on the use of “uncertainty phrases,” I often emphasize that the word “likely” is not an adverb tied to any particular notion, but one that can be used to qualify likeliness, confidence, and risk.  Of course, people probability consider how they feel about a hazard when judging whether the probability, or rather risk to them, is acceptable.  Others, particularly when speaking about finances, use risk to describe uncertainty - the higher the risk, the more uncertain the outcome.  The philosopher Frank Knight sides with these interpretations in his description of “risk proper,” or measurable uncertainty, described in Risk, Uncertainty, and Profit.  Most people argue that the only measure of uncertainty, at least when it comes to gambling situations, is probability, so what Knight is suggesting is that assessing “risk proper” is equivalent to a probability assessment.  But Peter Sandman suggests that what people really mean by risk is how outraged they feel about the situation.
• Safe: To risk people, safety is the judgment of risk tolerance.  If we are safe, then the risk does not exceed some threshold value (whether implicit or explicit).  To laypeople, “safe” = “no risk,” that is they treat it as a binary concept - you are either safe or you are not.  Or rather, there is risk or there is not.  I suppose the same reasoning can be extended to the word secure: to risk people, if we are secure, then the residual adversary risk is low enough for us to accept; to laypeople, “secure” = “no harm will come to them” in the event of an attempt.  Relative statements about safety and security are unambiguous though - to say something is more or less safe or secure than another thing is perfectly acceptable.
• Prepared:To be prepared means that we possess the capabilities and vigilance necessary to deal with a hazardous situation when it arises.  To risk people, preparedness is tied to risk acceptability - if we are prepared, then we have the capabilities needed to keep risk overall at an acceptable level.  To laypeople, prepared, like safe and secure, is taken to mean no (or perhaps minimal) harm will come to them.
• Confident: To say to someone else that you are confident when you are merely hopeful is not okay.  In the eyes of laypeople, confident = surety, though perhaps not so much anymore if the word has lost its meaning in the eyes of risk communication consumers. 

From my experience, I have five types of phrases to add:

• [Low/Moderate/High] Confidence:Philosophically speaking, to the analyst, anything said with a non-zero degree of confidence implies some degree greater than even odds of being correct.  This means that both “low confidence” and “high confidence” judgments are believed to be the right answer vice any alternative, but “low confidence” statements are afforded less commitment and as such are pegged to a representative probability value closer to 0.5 than a “high confidence” judgment.  To the decision maker, however, the scale may be expanded from a half probability scale to a full probability scale, where the words “low,” “moderate,” and “high” span the entire range.  So when the analyst says something with “moderate” confidence to indicate, say, a 75% chance of being correct, the decision maker might see it as a 50/50 judgment.  I would love to experiment with this to see whether or not what I just described is true.
• “In General”:  When mathematicians use the phrase “in general,” they mean what they say applies to all cases.  When lay people use the phrase in general, they mean that what they say is believed to apply to a simple majority of cases.
• Likely, Probable [and other uncertainty phrases]:  To risk people, the word likely conveys some degree of likeliness that exceeds 50%.  To laypeople, likely may communicate likeliness or risk.  In the latter, one might find that something deemed “likely” to a layperson may have an objectively low probability of happening, yet a high enough impact if it does to warrant use of the term in their non-probabilistic minds.  But whoever said words like “likely” and “probable” can only be used in the context of probability theory?  After all, what came first - the word “probable” or the “theory of probability?”
• Likelihood versus Likeliness: To mathematicians, “likelihood” means something very specific.  The likelihood of something in the context of Bayes theorem is the functional expression Pr(B|A) (read as “the probability of B given A) whose input argument is “A.”  That is, the “likelihood” is the hypothetical probability distribution constructed over a space of events conditioned on the occurrence of “A.”  The “likelihood function” or simply “likelihood” L(A|B) is proportional to Pr(B|A).  To non-mathematicians, including most (if not all) dictionaries, “likelihood” describes the notion of chance, where probability is one such measure of likelihood for an event.  According to WordReference.com, the word “likeliness” is an equivalent word for “likelihood,” but doesn’t carry with it all the mathematical baggage that might confuse a mathematician.  This is why I always use the word “likeliness” to characterize the notion of chance instead of “likelihood.”
• Possible: To mathematicians and risk people, a “possible” event is one that carries with it a non-zero probability.  More specifically, a possible event is one that is admitted into the set of alternatives (sample space) for a given question.  To non-mathematicians and laypeople, the word “possible” may be used to describe degree of chance or even risk.  How often have you heard people use possible to convey the likeliness of an event?  I read a study published by Sarah Lichtenstein and J. Robert Newman in 1967 (Psychonomic Science, Vol. 9, No. 10, pp. 563-564) showed that a group of 177 people, when individually asked to place numbers on words that convey uncertainty, could not agree on a probability value for the word “possible.”  The results showed a range of responses spanning probabilities of 0.01 to 0.99, with a median at 0.49.  What does this say?  To me this study makes my point - possible means that the probability is greater than 0, but we don’t know where.  But it also says that, at a micro level, possible might actually assign a value to possible.  Fortunately, the word “impossible” does not suffer the same ambiguity.

I am curious to hear your thoughts on these and other words that we should be careful about using in the context of risk communication, or “analytic communication” for that matter.