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Comment by nuancebydefault | Hacker News Reader

I'm a bit confused. Maybe i did not pay enough attention but... Does it stop the first simulation when there are _any_ 2 people with a same birthday, or when someone has _my_ birthday? I think the latter will take more people on average.

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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.

Thanks for that. I believe the fact that it asks for a birthday puts people's brain in a mode where the awe at the end is bigger.

Related, having flat tires on a car seems to come in little bursts,like 10 years none and then 2 in a year.

Can confirm, but both times it was a screw or something in my tire so I presume someone dropped some at a point of my commute.

I'd expect flats on cars to be correlated. People tend to buy tires in sets, so age related factors affect them all. Similarly they tend to get driven on the same roads, so are subjected to similar environmental damage.

Also, people are good at noticing patterns that don't exist, so that's a possibility too.

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