# Documentation/Calc Functions/NEGBINOMDIST

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NEGBINOMDIST

## Category:

Statistical Analysis

## Summary:

Calculates the negative binomial distribution for the given data about the number of failures, successes, and the probability of success for each attempt. This function uses probability mass function for all calculations.

## Syntax:

NEGBINOMDIST(X; R; SP)

## Returns:

Returns a real number which is a probability mass function value for the negative binomial distribution with the count of the unsuccessful test as X, successful tests as R, and the probability of success as SP.

## Arguments:

X is an integer value or a reference to the cell containing that value which represents the value returned for unsuccessful tests.

R is an integer value or a reference to the cell containing that value which represents the value returned for successful tests.

SP is a real number between 0 and 1 or a reference to the cell containing that value which is the probability of the success of an attempt.

• If R is less than 1 or X is less than 0 then the function returns an error value.
• If R or X are non-integer values then the function takes the floor of their value, i.e. they are truncated to integers.
• If SP is greater than 1 or less than 0, then the function returns an error value.

## Additional details:

• The formula for NEGBINOMDIST is:

If (X + R - 1)=>0 then

where x = X, r = R and p = SP

• For more details on the negative binomial distribution, visit Wikipedia.

## Examples:

Formula Description Returns
=NEGBINOMDIST(5;12;0.5) The function calculates the probability massfunction for the negative binomial distribution for the given arguments. 0.0333251953125
=NEGBINOMDIST(5;-4;0.5) The function returns an error value since R is less than 1. Err:502

NEGBINOMDIST