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Paul
Posts:
440
Registered:
2/23/10


Probability of selecting {n1,n2} from N tickets
Posted:
Sep 23, 2012 1:59 AM


In an example of the likelihood function, http://en.wikipedia.org/wiki/Likelihood_function#Example_2 describes an experiment in which two tickets are chosen from N tickets numbered from n1 to nN. Given integers n1 and n2, with n2>n1, the probability of selecting {n1,n2} is given as 1/(N choose 2). But there are N ways to choose n1, and N1 ways to choose n2; hence, there are N(N1) ways to choose {n1,n2} should be N(N1), which is certainly not (N choose 2). What am I missing?



