[hamiltonc]

Statistics and probability.

I've lost count how many times I inferred stuff by common sense and hunch, just to be proved wrong.

Our intuition is mostly off for statistical phenomena like confidence levels, odds of something happening again given some sample, some event being (statistically) relevant or not, etc.

[ahpearce]

I have a Bachelor's and Master's in stats, more or less, but my confidence is still extremely low.