NEGBINOM.DIST

NEGBINOM.DIST(number_f, number_s, probability_s, cumulative)

Returns the probability distribution function OR the cumulative probability function for a negative binomial distribution.

number_f	The number of failures.
number_s	The threshold number of successes.
probability_s	The probability of a success.
cumulative	A logical value indicating the type of function to use: False (or 0) = individual probability (equal to) True (<> 0) = cumulative probability (equal to or less than)

REMARKS

* The negative binomial distribution is a discrete distribution
* This function returns the probability that there will be "number_f" failures before the "number_s"-th success, when the constant probability of a success is "probability_s".
* For example, you need to find 10 people with excellent reflexes, and you know the probability that a candidate has these qualifications is 0.3.
* This function calculates the probability that you will interview a certain number of unqualified candidates before finding all 10 qualified candidates.
* The "number_f" and "number_s" are truncated to integers.
* If any of the arguments are not numeric, then #VALUE! is returned
* If "probability_s" < 0, then #NUM! is returned.
* If "probability_s" > 1, then #NUM! is returned.
* If "cumulative" = False, then the height of the curve at "x" is returned.
* If "cumulative" = True, then the area under the curve to the left of "x" is returned.
* If ("number_f" + "number_s" - 1) = 0, then #NUM! is returned.
* The equation for the negative binomial distribution is: ??
* You can use the BINOM.DIST function to
* You can use the BINOM.DIST.RANGE function to
* You can use the BINOM.INV function to return the probability of getting (greater than) a particular value using a binomial distribution.
* This function was added in Excel 2010 to replace the NEGBINOMDIST function and include an option for cumulative probability.
* For the Microsoft documentation refer to support.microsoft.com

	A
1	=NEGBINOM.DIST(0, 1, 0.25, FALSE) = 0.25
2	=NEGBINOM.DIST(0, 1, 0.5, FALSE) = 0.5
3	=NEGBINOM.DIST(1, 6, 0.5, FALSE) = 0.047
4	=NEGBINOM.DIST(10, 5, 0.25, FALSE) = 0.055
5	=NEGBINOM.DIST(10, 5, -4, FALSE) = #NUM!
6	=NEGBINOM.DIST(10, "some text", 0.25, FALSE) = #VALUE!