Conditional probabilities
Usually when someone confuses the probability of A given B and the probability of B given A they don’t really understand that these are different, and you have to point it out and explain it carefully. Richard David Prosser manages to be self-refuting,
And he added: “If you are a young male, aged between say about 19 and about 35, and you’re a Muslim, or you look like a Muslim, or you come from a Muslim country, then you are not welcome to travel on any of the West’s airlines…”
He accepted that most Muslims are not terrorists, but said it’s “equally undeniable” that “most terrorists are Muslims”.
actually pointing out himself that p(terrorist|Muslim) and p(Muslim|terrorist) are not remotely similar. In the same way, although most members of the Pakistan cricket team are Muslims, most Muslims are not members of the Pakistan cricket team.
That doesn’t handle the further pointless complication of ‘people who look like Muslims’, who, as far as I have been able to tell, are not over-represented among terrorists, but this site might be helpful for calibration.
Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »