This [XKCD comic](http://xkcd.com/1132/) has inspired me to note down (or copy over) some of the little thoughts I've had over the years on Frequentists vs Bayesians. ---- Back on my blog in 2008, I said that if I ever taught statistics, I'd write the following on the blackboard the first lecture: > Colin comes up to Barry and Frank and says, "hey guys! I have a coin here which is biased but I won't tell you which way or by how much. What's the probability of the next toss being tails?". Barry replied, "given what we know, it is 0.5". Frank looked astonished. "How can you say 0.5? Given the coin is biased, that's the one probability we know it can't be." Who is right, Barry or Frank? ---- Walter asks Barry, "what's the chance of rain tomorrow?". Barry replies, "80%". The following day it doesn't rain. Walter confronts Barry but Barry responds, "Oh, my prediction yesterday was spot on". ---- Could the previous story could be told exactly as-is with Frank instead of Barry? ---- Another fun blackboard problem in probability... > This broke my brain ... > ![BiV7NfECEAAE_uI.jpg](/media/168/BiV7NfECEAAE_uI.jpg) > — Siqi Chen (@blader) March 10, 2014