# Birthday Problem with Realistic Assumptions

## Main Question or Discussion Point

Hi, All:

The standard way of approaching the birthday problem, i.e., the problem of
determining the number of people needed to have a certain probability that
two of them have the same birthday, is based on the assumption that birthdays
are uniformly-distributed, i.e., that the probability of someone having a birthday
on a given day is 1/365 for non-leap, or 1/366 for leap.

But there is data to suggest that this assumption does not hold; specifically,
this assumption failed a chi-square at the 95% for expected-actual, for n=480,040
data points.

Does anyone know of a solution that uses a more realistic distribution of birthdates?

## Answers and Replies

Related Set Theory, Logic, Probability, Statistics News on Phys.org
This paper seems to be exactly what you're looking for--

http://www.jstor.org/pss/2685309

but you will need access to a JSTOR account to see more than the first page.

Last edited by a moderator:
Excellent, 'Awkward' , thanks.