[Rd] Problem with pbirthday (PR#7837)
andy.lynch at phpc.cam.ac.uk
andy.lynch at phpc.cam.ac.uk
Wed May 4 15:07:06 CEST 2005
Full_Name: Andy Lynch
Version: 1.9.1
OS: Windows
Submission from: (NULL) (131.111.86.211)
As I understand it, pbirthday(n,c,k) gives the approximate probability that we
see a class with k coicident people in it when n people are sorted into c
classes.
so the command
> pbirthday(4,classes=3,coincident=4)
should give the approximate probability that when four people fall into three
classes, all four end up in the same class. A probability that is clearly lower
than the presently returned value of 1.
It seems to me that the line in the function
if (n > classes) return(1)
is only relevant to the default case of coincident = 2. (Naturally, if there are
more people than classes, then at least one class must contain 2 people).
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