2 thoughts on “Miscellaneous links”

  1. A terroríst attack today doesn’t, a priori, incraese the odds of another one tomorrow, so no need to update priors. However seismic activity occurs in cycles, so an earthquake today REALLY DOES increase the odds of another tomorrow…

    For the doomed Concorde the situation was unclear immediately after the accident. If the crash was due to debris on the runway, there would be no need to update. If it was due to the age of the aircraft, a design fault or a Y2K problem, then one woiuld have to update .

    1. Hi Herman,

      I agree that if we know events cluster- that they have high auto-correlation, this makes sense. Earthquakes are a naturally occurring phenomena where this might be true.

      But the social events – 9/11, market crashes – we don’t know that they have a stable, objective auto-correlation. In fact, 9/11 made it abundantly clear that they don’t have a stable rate at all. What are the odds of 4 full commercial jet planes being hijacked at once, and used all used as missiles?

      Up to 9/11 most passengers would not interfere with a hijacked plane. Most hijackings had been for escape reasons, and no-one had used a commercial jet as a missile before. The passengers on flight 93 might not have reacted the way they did, if they did not think one hijacking wasn’t related to another. They immediate assumed a nearly perfect correlation.

      Given a coordinated attack across 4 flights, how would we know that the auto-correlation hadn’t just increased? Perhaps bombs, rather than hijackers would be used. Data isn’t sufficient to answer that question.

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