Comments on: Experts Predict 2010 Will Be Terrible

By: Stephen Schwartz

Stephen Schwartz — Mon, 04 Jan 2010 17:11:04 +0000

Perhaps we should also pay heed to the recent JASON report Rare Events on the inherent difficulties in forecasting such occurrences: “Predicting WMD-T [Weapons of Mass Destruction-Terrorism] rare events is obviously a desirable goal. This has been stated many times by DoD, DHS, the IC, academic researchers, and others. However, it is simply not possible to validate (evaluate) predictive models of rare events that have not occurred, and unvalidated models cannot be relied upon.”

By: Josh

Josh — Tue, 29 Dec 2009 04:18:42 +0000

As a famous expert allegedly once remarked, “It’s tough to make predictions, especially about the future.” But this does not explain the consistent lean toward pessimism. There, Betts may be on the money.

Another explanation, though, is the difficulty of estimating very small probabilities. There is a general tendency to overestimate them. For this reason, there may be better ideas than just asking for the probability of each event.

By: John Field

John Field — Sun, 27 Dec 2009 18:37:17 +0000

Is it the case that a single variable – like pessimism – can explain much of the response weight?

How about an eigenvector decomposition of the data to look for this sort of thing?

Is the raw anonymized data available?

By: MK

MK — Sun, 27 Dec 2009 03:07:27 +0000

Alex:
The five year window of maximum danger has been a constant of sorts. As I recall (and stand to be corrected), it was present in the analysis of NSC-68, Gaither, Team A/B, and most recently, the WMD Commission.

By: VS

VS — Sun, 27 Dec 2009 00:32:41 +0000

Those asked have applied for grants.

By: Alex W.

Alex W. — Sat, 26 Dec 2009 22:58:56 +0000

An aside: One of the many good things that Michael Gordin does in his new book, Red Cloud at Dawn, is to show how the estimate of “five years” until the USSR had a bomb was prevalent through the late 1940s, but nobody advanced the counter. Thus is was “five years” in 1945, and “five years” in 1946, and “five years” in 1947, and so on, until 1949 when suddenly the Russians had the bomb “five years” before anyone expected them to. Personally, I’m unclear what “10% chance” really means in this kind of prediction. The use of probabilistic terms doesn’t strike me as the best way to conceptualize this kind of threat, at least not in this kind of vague way.

By: AndyJ

AndyJ — Sat, 26 Dec 2009 21:09:11 +0000

let’s assume that the probabilities of a nuclear/biological/chemical/radiological attack are independent. using figures

P(nuke) = 0.1
P(bio) = 0.2
P(chem) = 0.2
P(rad) = 0.3

then we can use the inclusion/exclusion rule to see that

P(disaster in 5 years) = 0.6168

and if we make another baseless assumption, that the average rate of attacks is 0.6168 per 5 years, then the distribution of time till the first attack, T ~ Exp(0.6168/5). so:

P(attack this year | no attack in the last 4) = P(attack this year) = P(T < 1) = 0.1161

of course the assumptions stated make such figures worthless – i did this more to demonstrate intuition isn’t much use when it comes to probability.