The `POISSON.DIST` function in Excel is used to calculate the Poisson probability distribution, which expresses the probability of a given number of events occurring in a fixed interval of time or space. This function can be useful in fields like operations research, reliability engineering, and any other field where you’re dealing with events occurring randomly over a continuum.
Syntax
POISSON.DIST(x, mean, cumulative)
Arguments
- x: The number of events. This has to be a non-negative integer.
- mean: The expected number of events, specified as a positive number.
- cumulative: A logical value that determines the form of the function.
- If `TRUE`, `POISSON.DIST` returns the cumulative distribution function, which is the probability of having up to `x` events.
- If `FALSE`, it returns the probability mass function, which is the probability of having exactly `x` events.
Examples
=POISSON.DIST(3, 2, FALSE)
- Exact Number of Events
- If you want to find the probability of exactly 3 events happening, given an average rate of 2 events:
This will return the probability of exactly 3 events occurring.
=POISSON.DIST(3, 2, TRUE)
- Cumulative Probability
- If you want to find the probability of 3 or fewer events happening, given an average rate of 2 events:
This will return the cumulative probability of 0, 1, 2, or 3 events occurring.
Notes
- Ensure that the `x` value is a non-negative integer; otherwise, Excel will return an error.
- Both the `mean` and the `x` values should make logical sense in the context of your problem; double-check the domain and potential restrictions of your dataset.
- The Poisson distribution assumes that each event is independent, and the average rate (mean) remains constant over time.
By understanding how to use the `POISSON.DIST` function effectively, you can leverage it to calculate probabilities related to random events efficiently in Excel.
Unlock Your Potential
Excel
Access
Power BI
