If half of an airline's flights are full and half are empty, passengers will complain that the flights are full every time, contrasting with the assessment of the crew who report that half of the flights are empty. How do you call this effect/paradox? (I forgot)
The same effect explains that if you have an average number of friends (= popularity), more than half of your friends are more popular than you.
Or when your doctor tells you you're in average physical condition but each time you go cycling, most cyclists you come across are faster than you (because the fast cyclists are also the ones who spend the most time on the roads and are encountered disproportionately).
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@mjambon You are describing quite a few things.. namely survivorship bias, and regression to the mean are most notable.
I suspectit may not be obvious why its survivorship bias.
The bicycle example lines up with this because the best cyclists survive the exervise longer, thus you have a samping bias towards those who survive the longest on the road,
Same with the friends examples... The most popular people tend to survive more friendships, meaning more popular people are more likely to have friends (including you).
@mjambon You may also be thinking the Cauchy-schwartz inequality, which describes the math behind the scenario re: friendship you mentioned. That is called the friendship paradox.
@freemo oh, interesting note regarding the friendship paradox:
> In contradiction to this, most people believe that they have more friends than their friends have.
I would explain this by the fact that we spend more time with people who have fewer friends than average. (not sure if it's a hard rule or if depends on the shape of the friendship graph)
@mjambon this seems more like a social element than a statistical one.. but yea i get that.