Open thread, August 19-25, 2013

David_Gerard

If it's worth saying, but not worth its own post (even in Discussion), then it goes here.

I have made it up to episode 5 of Umineko, and I've found one incident in particular unusually easy to resolve (easy enough that though the answer hasn't been suggested by anyone in-game, I am sure that I know how it was/could be done); I'm wondering how much it is due to specialized knowledge and whether it really looks harder to other people. (Because of the curse of knowledge, it's now difficult for me to see whether the puzzle really is as trivial as it looks to me.) So, a little poll, even though LWers are not the best people to ask.

In episode 5, an unknown caller phones Natsuhi in her locked personal room. He says he's predicted her favorite season of the year, and asks her what it really is. She replies 'winter', and he says that is what he predicted. She is skeptical and he tells her to look underneath a clock in her room. She does and finds a slip of paper with the word 'winter' on it: he had been there earlier and left it as proof of his prediction. Natsuhi is shocked and mystified.

How sure are you that you know how he did it?

[pollid:549]

How would you rate your familiarity with cryptography?

[pollid:550]

(Please rot13 any replies.)

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0gwern13y

Thanks for all the poll submissions. I decided since I just finished Umineko, this is a good time to analyze the 49 responses. The gist is that the direction seems to be as predicted and the effect size reasonable (odds-ratio of 1.77), but not big enough to yield any impressive level of statistical-significance (p=0.24): R> poll <- read.csv("http://dl.dropboxusercontent.com/u/182368464/umineko-poll.csv") R> library(ordinal) R> summary(clm(as.ordered(Certainty) ~ Crypto, data=poll)) formula: as.ordered(Certainty) ~ Crypto data: poll link threshold nobs logLik AIC niter max.grad cond.H logit flexible 48 -30.58 67.16 5(0) 5.28e-09 2.9e+01 Coefficients: Estimate Std. Error z value Pr(>|z|) Crypto 0.571 0.491 1.16 0.24 Threshold coefficients: Estimate Std. Error z value 0|1 1.988 0.708 2.81 1|2 3.075 0.822 3.74 (1 observation deleted due to missingness) R> exp(0.571) [1] 1.77 Or if you prefer, a linear regression: R> summary(lm(Certainty ~ Crypto, data=poll)) Call: lm(formula = Certainty ~ Crypto, data = poll) Residuals: Min 1Q Median 3Q Max -0.409 -0.287 -0.287 -0.164 1.836 Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 0.164 0.151 1.09 0.28 Crypto 0.122 0.117 1.05 0.30

1gjm13y

I'm rather alarmed at how many people appear to have said they're very sure they know how he did it, on (I assume, but I think it's pretty clear) the basis of having thought of one very credible way he could have done it. I'm going to be optimistic and suppose that all those people thought something like "Although gwern asked how sure we are that we know how it was done, context suggests that the puzzle is really 'find a way to do it' rather than 'identify the specific way used in this case', so I'll say 'very' even though for all I know there could be other ways'. (For what it's worth, I pedantically chose the "middle" option for that question, but I found the same obvious solution as everyone else.)