Chapter 33: Analyzing Data with the Analysis ToolPak
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FIGURE 33.10
Output from the paired T-test dialog box
Z-test (two-sample test for means)
The T-test tool is used for small samples; the Z-test tool is used for larger samples or popula-
tions. You must know the variances for both input ranges. Generally, use a T-test when your
sample size is less than 30 and you don’t know the standard deviation of the population.
Otherwise, use the Z-test.