## Quick Reference

A test, using a sample of *n* independent observations, of the null hypothesis that a normal distribution with variance *σ*^{2}, has mean *μ*. Writing the sample mean as *x̄*, the test statistic is *z*, given by In the case where the alternative hypothesis is that the mean is not *μ*, then, if |*z*| > 1.96, there is evidence to reject the null hypothesis at the 5% significance level in favour of the alternative hypothesis. See hypothesis test.

**From:**
z-test
in
A Dictionary of Statistics »

*Subjects:*
Psychology — Probability and Statistics.

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