Description Computes the negative binomial distribution, which is used to determine probabilities on repeated tests where each test is independent of every other test (that is, the probability is the same for each test).
Syntax NEGBINOMDIST (failures, threshold, probability)
| Argument | Description |
|---|---|
| failures | The number of failures you expect in the trial. It must be a positive integer or 0. |
| threshold | The number of successes the trial requires. It must be a positive integer. It may not be 0. |
| probability | The chance of success on an individual attempt in the trial. It must be a number larger than 0 and smaller than 1. For example, the probability of throwing heads on a coin toss is 0.5. |
Remarks Coin tosses or die rolls are examples of uses for NEGBINOMDIST. The probability returned measures the likelihood that there will be a certain number of failures before a certain number of successes occurs. This can be used to determine how many tests to run to achieve the desired results.
NEGBINOMDIST is similar to BINOMDIST, only in NEGBINOMDIST the number of successes is fixed and the number of trials is variable, while in BINOMDIST the number of successes is variable and the number of trials is fixed.
Equation
...where f is failures, t is threshold, and p is probability.
Example This function returns 0.1875:
See Also BETADIST, BINOMDIST, CHIDIST, COMBIN, CRITBINOM, EXPONDIST, GAMMADIST, NORMDIST, POISSON
