Syntax
NEGBINOM.DIST(failures, successes, prob, cumulative)
| Parameter | Description |
|---|---|
| failures | Parameter of the NEGBINOM.DIST function. |
| successes | Parameter of the NEGBINOM.DIST function. |
| prob | Parameter of the NEGBINOM.DIST function. |
| cumulative | Parameter of the NEGBINOM.DIST function. |
Examples
3 rejections before 5th sale
Formula
=NEGBINOM.DIST(3, 5, 0.4, FALSE)
Returns ~0.1003. With a 40% close rate, there is about a 10% chance of encountering exactly 3 rejections before making the 5th sale.
At most 10 failures before 3 successes
Formula
=NEGBINOM.DIST(10, 3, 0.3, TRUE)
Returns ~0.7975. With a 30% success rate, there is about an 80% chance of needing 10 or fewer failures before achieving 3 successes.
Modeling customer acquisition attempts
Formula
=NEGBINOM.DIST(7, 2, 0.15, TRUE)
Returns ~0.5272. With a 15% conversion rate, there is about a 53% chance of getting 2 customers within 9 total attempts (7 failures + 2 successes).
Common Errors
#NUM!
Number_f must be >= 0, number_s must be >= 1, and probability_s must be between 0 and 1.
#VALUE!
Occurs when arguments are non-numeric.
Tips
Failures, not total trials
The first argument is the number of failures, not the total number of trials. Total trials = failures + successes.
Relationship to geometric distribution
When number_s = 1, the negative binomial becomes the geometric distribution — the number of failures before the first success.
Use cumulative for planning
Set cumulative=TRUE to answer 'what is the probability of reaching my target within a total of k+s trials?' This helps with project planning and resource allocation.
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