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Unformatted text preview: f x = 1, 2, 3, . . .
µ = E (X ) = p
σ 2 = Var(X ) = Math 30530 (Fall 2012) q
p2 Discrete Random Variables October 7, 2012 4 / 10 The Negative Binomial random variable
Name: NegBinomial(r , p)
When to use: When you want to count how many times you have
to repeat the same experiment, independently of each other,
until you ﬁrst have some predetermined number of successes
r : the number of successes you are aiming for
p: the probability of success on each individual trial Mass function:
pX (x ) = x −1
r −1 0 q x −r p r if x =...
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- Spring '11