Use 1-Sample Z to estimate the mean of a population and to compare it to a target value or a reference value when you know the standard deviation of the population. Using this test, you can do the following:

- Determine whether the population mean differs from the hypothesized mean that you specify.
- Calculate a range of values that is likely to include the population mean.

For example, a quality analyst uses a 1-sample Z-test to determine whether the mean thread length of bolts meets the target of 20mm. If the mean differs from the target, the analyst uses the confidence interval to determine whether the difference is practically significant.

- Mac:
- PC:

If you do not know the standard deviation of the population, use a 1-Sample t.