> Sure, a probability of having many tails continously is low but how is it not random? Randomness is never about the output; it is a property of the source.

> Sure, a probability of having many tails continously is low but how is it not random? Randomness is never about the output; it is a property of the source. So what is not random, is that the frequency of people that output repeating sequences is higher than the quotient of that sequence among all possible sequences of the same size. The issue of the initial paper is that it claims to conclude that people aged > 60 are less random, when they simply output a fully-repeating sequence with a slightly higher rate (which is not surprising taking into consideration that there are much, much fewer of them).