Question

what is negative binomial distribution and its mean and varrience

Answer 1

| p) = p(1 − p)x−1, x = 1,2,..., which defines the pmf of a geometric random variable X with success probability p. X can be interpreted as the trial at which the first success occurs, so we are “waiting for. a success”. The mean and variance of X can be calculated by using the negative binomial.