# WorksheetFunction.Z_Test (Excel)

Returns the one-tailed probability-value of a z-test. For a given hypothesized population mean, Z_Test returns the probability that the sample mean would be greater than the average of observations in the data set (array); that is, the observed sample mean.

If array is empty, Z_Test returns the #N/A error value. Z_Test is calculated as follows when sigma is not omitted:

**Z_Test** (Arg1, Arg2, Arg3)

```
Dim dblArg2 As Double: dblArg2 =
Dim dblZ_Test As Double
dblZ_Test = WorksheetFunction.Z_Test(Arg1:=, Arg2:=dblArg2)
```

## Arguments

Arg1, Arg2, Arg3Arg1 - Array is the array or range of data against which to test the hypothesized population mean

Arg2 (Double) - The value to test.

Arg3 - Sigma is the population (known) standard deviation. If omitted, the sample standard deviation is used