I think it is closer to the reason why it is surprisingly difficult to throw a rock through a wire fence even when the rock is much smaller than the holes in the fence. We tend to underestimate the area of interaction between the rock and the fence.

If you take a locker in the middle, there will be 8 lockers right next to yours, which may represent a sizable fraction of the total number. Combine that people are not random and that they tend to forget about the times where it doesn't happen and it may seem like it happens all the time even when it is uncommon on average.

(Apologies for the fun-ruining comment.)

For it to be a true analogue if the birthday paradox, it would have to happen rarely to you individually, but surprisingly often to one pair of people in the locker room when there are a smallish number in there.

There’s also the Aisle at a Show Paradox: as a tall guy, no matter where I stand at a concert I always seem to end up being the guy people decide is the aisle and jostle their way around me when transiting from one area of the venue to the other.

I haven’t tested this hypothesis yet but I suspect I could be wandering the desert and out of no where someone will try to slink past me while saying excuse me and spilling my canteen all over.

Assuming you don't have an automated system to give away locker keys, wouldn't this be explained by the fact that gym front desk is more likely to give out the lowest number available and as you took X, they will give out X+1 for the next person?

>awkwardly jostling away

I imagine it’d be more fun in a group setting?

I have FOUR significant people in my life with November 15th birthday, so I just groaned when I saw the author’s birthday.

And happy birthday phito :)

Plenty of November birthdays because it's cold in Februrary (11 - 9 = 2).

Happy birthday to you and me, fellow Scorpio.

Happy birthday :)

Thanks for all your birthday wishes <3

Nothing unfortunate about having a birthday today.

Happy Birthday!

At the end, if you ask for more nerd stuff, it displays a histogram of submitted birthdays. There’s two big outliers: one in November and one in January.

It looks like many people submit January 1 or the current date.

The website is being purposefully obtuse and the birthday paradox is a "paradox" because it's sometimes formulated in the same way as the website. In other words, you are completely correct that the intersection of any two birthdays is significantly more likely than the intersection of a particular birthday.

The Birthday Paradox is about a group of people sharing at least one birthday between them. If it was at least 1 person out of 23 people sharing YOUR birthday then the odds would be 1 - (364/365)^23 which is around 0.06 (or 6% chance). So, yes, this scenario is a lot less likely.

Remember that the seasons are inverted on the other side of the equator. (Granted, the population splits something like 90/10 but still.)

Yes, it's also extremely unlikely.

The actual distribution in developed countries is not uniform: there is a spike at the end of September (because many more people make babies at or around New Year's Eve) and a considerable drop on Dec. 25th (because people will avoid that date and provoque the birth some days before in case it might happen).

Also, on the site there is a huge spike on Nov. 15 which, incidentally, is the birthday of the author: maybe they tested it many times?

I wonder if modern living has pretty much made this a non-factor. We have things to entertain ourselves regardless of the duration of light outside and so we're no longer left sitting at home in front of the fire bored, we're sitting at home in front of the fire playing with our phones. Less likely to bow-chicka-bow-wow out of boredom.

Weird how, coincidentally, 3x as many people are born on Nov 15 as any other day

I tried it and it just gives the same continuation that talks of a shared birthday.

There is one birthday that is far less likely than others, courtesy of leap years. All other are roughly similar, with small seasonal variation.

That would not be a surprise to me :)

Most people access they WEB via the phone, I would expect it is up to 80% browse on their phone.

Also https://matt.might.net/articles/counting-hash-collisions/

Wait, how is the math clear? There was no math presented on the site, I didn't see a single formula

> While the math is clear, I'm a bit annoyed by the label "paradox" as the whole setup is too simplistic and reductionistic.

https://en.wikipedia.org/wiki/Paradox#Veridical_paradox

(also https://www.youtube.com/watch?v=ppX7Qjbe6BM for a 40min video discussing the weird usages of the word "paradox")

Wait, what?

Are you saying that income influences what time of the year you are born?

The paradox doesn’t talk about meeting your birthday sibling, but meeting two people who are birthday siblings.

So by the time the 12 year old has met ~20 people, there is a 50/50 chance that amongst those 20, there’s a birthday pair.

Could you explain more what you mean? Other than certain holidays perhaps causing a higher chance of alone time for future mom and dad, I don’t see what you mean, and I don’t understand your last paragraph.