Welp. It seems that the reason the birthday paradox has always felt like a confusing concept to me, is because it has a reputation for being counterintuitive (and many explanations try to address that counterintuitive aspect) but it has never actually been counterintuitive for me in the first place so I didn't have that frame of reference, and I was looking for a 'gotcha' that wasn't there...
The Dutch Wikipedia article on it actually explained *why* this is confusing to people, which ironically is what made me realize this 🙃 Turns out it works pretty much just exactly how I expected
@aetios Question is "if you have N people, how big is the chance that at least two birthdays overlap?" and apparently people frequently guess that this grows linearly, ie. chance of 4 people having overlap is twice as much as 2 people having overlap.
When in reality, AIUI, the calculation works more like 2x(2-1) vs. 4x(4-1) because *both* 'sides' of the overlap calculation have actually grown, not just one.
@aetios Right but that's the thing, that's intuitively obvious to me! But apparently not to a lot of people, and that's why such a fuss is made over this concept 🙃
@joepie91 @aetios I had trouble understanding it because that was how it was explained to me at first; the chance that any birthday intersects with mine is 50% when there are 23 people in the group.
I suspect the one who explained it to me didn’t understand the paradox themselves, but just liked to spread the factoid.
