4 ms·
>Bob claims that since the probability of getting both his and Alice’s sequence is the same (2−20 ), it proves that there was no foul-play involved. ..and Bob
by copx 3y ago
>Bob claims that since the probability of getting both his and Alice’s sequence is the same (2−20
), it proves that there was no foul-play involved.
..and Bob is 100% right.
>Bob credits his excellent luck. Alice is smart and cannot be easily convinced. She get’s back at Bob by claiming that probability cannot be used in this context as it reveals no information regarding the randomness of the obtained sequences. One can take a quick glance at the obtained sequences and easily point out that Alice’s sequence is more random than Bob’s sequence.
No, it is not. Given a perfectly random coin toss Bob's sequence is indeed just as likely as Alice's sequence and in no way "less random" because both sequences result from the same randomness with equal probability.
A nice example of human intuition being at odds with probability math, though. Bob's result seems less likely but it really is not.
Which reminds me that I actually had to write my own computer simulation of the Monty Hall Problem before I was willing to believe the correct answer.
I think (most?) human brains have a bug in the "understanding probability" subroutine.
- ptero 3y agoNot quite. Specifically, assuming independent random tosses A and B sequences are equally likely. No objection here. But the question posed is different: given a specific sequence, how likely it to have come from independent coin tosses? That is, how likely is it that Bob is cheating and his sequence was in fact not a sequence of a fair coin tosses. And for this KC is a reasonable measure. My 2c.
- Gimpei 3y agoCouldn’t you say that the distribution of tosses is less likely in the case of Bob?
- Hunpeter 3y agoThe "bug" in this case imo, is that we interpret A's sequence as "random garbage" without regard to the actual contents, whereas we interpret B's as "all Ts". The question our brain asks then is "is it more likely to get random garbage or all Ts?"
- nerdponx 3y agoRight. It might be more interesting to consider the count of Ts and Hs instead of considering exact sequences.