BUS 310
Notes regarding Two-Sample t-Tests and ANOVAs

In Chapter 9, we learned how to conduct a t test of a hypothesis when we were testing the mean of a single sample group against some pre-determined value (i.e., the 21.6 gallons of milk consumption as the national average). This week, in Chapter 10, we will see how to test hypotheses that involve more than one sample group—such as testing to see if males are significantly taller than females. If we have two groups, then the technique that we will use will still be a t test. If we have more than two groups, then we will have to use a different test called Analysis of Variance (ANOVA, for short).

The good news is that the decision rules for hypothesis testing that we learned last week are still exactly the same:

Set #1:
If the absolute value (ignore any negative sign) of the test statistic is greater than or equal to the critical value, then you reject the null. If the absolute value of the test statistic is less than the critical value, you do not reject the null.

Set #2: If the p value is less than or equal to α, reject the null. If the p value is greater than α, do not reject the null.

(Remember that we must either reject or not reject the null—we never accept the null.)

In order to conduct these tests, we will need to use the data analysis feature of Excel, which probably is not installed for you, but that’s OK, because it’s available and pretty simple to install—just follow these steps:

1. Start Excel
2. Click on the Office Button (the round circle in the top left corner)
3. Click on the Excel Options button (bottom right on the popup)
4. In the menu on the left hand side, click on Add-Ins
5. At the bottom center, click the Go… button
6. Check the first two boxes (Analysis ToolPak and Analysis TookPak-VBA), and then click OK

After installing the add-in, then you