Chris Brakebill’s Posterousness

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Aren't analysts good at math?

Jonathan says he "couldn’t find compelling evidence" that AT&T's contract with Apple ends this year. He gives it a 50% chance. Additionally, there's a 25% chance that AT&T would bid for -- and win -- another year of exclusivity. Add them up, you get 75%.

This guy is an analyst? Let's go for a quick review of basic probability. By his guess, there's a 50% chance Apple's contract w/ AT&T is over. And then, given that the contract is over, there's a 25% chance AT&T would win the bid for another year.

Basic conditional probability says P(A and B) equals P(A) * P(B given A). So the chance Apple stays w/ AT&T is 25% * 50% which is 12.5%. Pretty damn different from 75%....

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