# PoissonFrequency Script and chart function

`PoissonFrequency()` returns the Poisson probability distribution.

Syntax:

PoissonFrequency(value, mean)

Return data type: number

Arguments

| Argument | Description |
| --- | --- |
| `value` | The value at which you want to evaluate the distribution. The value must not be negative. |
| `mean` | A positive number defining the average outcome. |