Microsoft Office

Part V
Analyzing Data with Excel
The Sampling tool
The Sampling tool generates a random sample from a range of input values. The Sampling tool can help you
to work with a large database by creating a subset of it. The Sampling dialog box appears in Figure 38.10.
This procedure has two options: periodic and random. If you choose a periodic sample, Excel selects every
nth value from the Input range, where n equals the period that you specify. With a random sample, you simply
specify the size of the sample you want Excel to select, and every value has an equal probability of being
chosen.
FIGURE 38.10
The Sampling dialog box is useful for selecting random samples.
The t-Test tool
Use the t-Test to determine whether a statistically significant difference exists between two small samples.
The Analysis ToolPak can perform three types of t-Tests:
n
n
n
Paired two-sample for means: For paired samples in which you have two observations on each
subject (such as a pretest and a post-test). The samples must be the same size.
Two-sample assuming equal variances: For independent, rather than paired, samples. Excel
assumes equal variances for the two samples.
Two-sample assuming unequal variances: For independent, rather than paired, samples. Excel
assumes unequal variances for the two samples.
Figure 38.11 shows the dialog box for the Paired Two Sample for Means t-Test. You specify the significance
level (alpha) and the hypothesized difference between the two means (that is, the null hypothesis).
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