NEGBINOMDIST(number_f, number_s, probability_s)

The NEGBINOMDIST function calculates the negative binomial distribution.

This is a measure of the probability that a certain number of failures will occur before the nth success, given that the probability of success is constant. It is used in situations where the number of trials is variable and each trial is independent of the others, but the number of successes is fixed.

The function arguments are:

number_f

the number of failures

number_s

the number of successes

probability_s

the probability of a success

For example, we want to know the probability of getting exactly 10 tails ("failures") before we get 12 heads ("successes") in a coin-tossing experiment. The probability of a success is constant at 0.5. The formula:

NEGBINOMDIST(10, 12, 0.5)

returns 0.084094 as the probability.

See also:

Other statistical functions