NEGBINOMDIST Function in Excel calculates the Negative Binomial Distribution for a given set of parameters. Negative binomial distribution gives the probability that there will be a specified number of failures before a required number of successes is achieved.
Negative Binomial Distribution Formula:Negative Binomial Distribution Formula for rth success occurring on xth trial is shown below
x: is the number of trials
r: The required number of successes.
p: The probability of success on an individual trial.
q: The probability of failure on an individual trial (q= 1-p)
Syntax of NEGBINOMDIST Function in Excel:
number_f – The number of Failures encountered before the number of success.
number_s – The number of successes
probability_s – The probability of success(for a single trial).
Example of NEGBINOMDIST Function in Excel:
Let’s take an Example of Negative Binomial Distribution Function for the probability that the toss of a coin will result in exactly X Heads before 5 tossed Tails.
When we plot the above result with number of failures before the success on x axis. We will get the graph.