If X follows a multinomial probability distribution with P = [p0,p1,…,pj] (where p0 + … + pj = 1), then for K=[k0,…,kj] with k0 + … + kj = n, the probability that X=K is given by the multinomial command;
multinomial(n,P,K)= |
| (p0k0p1k1… pjkj. |
You will get an error if k0 + … + kj is not equal to n, although you won’t get one if p0 + … + pj is not equal to 1.
For example, if you make 10 choices, where each choice is one of three items; the first has a 0.2 probability of being chosen, the second a 0.3 probability and the third a 0.5 probability, the probability that you end up with 3 of the first item, 2 of the second and 5 of the third will be
or