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The `NEGBINOMDIST` function in Excel is used to calculate the negative binomial distribution, which is commonly applied in scenarios where you are modeling the number of failures before achieving a fixed number of successes in a sequence of independent and identically distributed Bernoulli trials.
Here’s how you can use the `NEGBINOMDIST` function:
Syntax:
NEGBINOMDIST(number_f, number_s, probability_s)
Parameters:
- number_f: The number of failures. This is a non-negative integer that represents the number of unsuccessful trials before you reach the set number of successful trials.
- number_s: The number of successes. This is the total number of successful trials you are aiming to achieve.
- probability_s: The probability of success on each individual trial. This value must be between 0 and 1.
Example:
Suppose you want to calculate the probability of having 3 failures before achieving 2 successes in a scenario where the probability of success on each trial is 0.5.
- number_f (Number of failures): 3
- number_s (Number of successes): 2
- probability_s (Probability of success per trial): 0.5
You would enter the function in Excel as:
=NEGBINOMDIST(3, 2, 0.5)
Important Notes:
- Ensure the parameters are set correctly: `number_f` should be a non-negative integer while `number_s` should reflect the number of successful outcomes you’re targeting.
- `probability_s` should be a fractional value representing the likelihood of success in each trial.
- The function returns a probability value, typically used in statistical analysis to model various real-world problems such as predicting the number of trials needed to achieve a certain number of events.
By properly setting up the `NEGBINOMDIST` function, you can leverage Excel to perform complex statistical calculations related to negative binomial distributions.