[...] The statement of the birthday matching problem is "If there are N people in a room, what is the chance that two of them have the same birthday?" Every statistical programmer implements the birthday matching problem at some point. Like estimating the value of pi and computing prime numbers, it is a classic problem that is popular because it is easy, fun, and surprising the first time you see the answer. I have used the idea of the birthday matching in several blogs, such as computing the probability that two people at a meeting have the same initials. I also examine the birthday-matching problem in Chapter 13 of my book, Statistical Programming with SAS/IML Software, both under the assumption that birthdays are uniformly distributed throughout the year and also under an empirical distribution of birthdays by using data from the National Center for Health Statistics (NCHS). The empirical distribution incorporates seasonal effects, as well as the effect of holidays on US births. …