One-Sample Hypothesis Testing Using MINITAB
The first instruction block in this section begins by describing the entry of data into the MINITAB data window. Alternatively, the data may be loaded directly from the data disk included with the text. The appropriate data file name is given at the top of the instruction block. Please refer to Appendix 1.1 for further information about entering data, saving data, and printing results when using MINITAB.
Hypothesis test for a population mean in Figure 9.9(a) on page 368 (data file: CreditCd.MTW):
• In the Data window, enter the interest rate data from Table 9.3 (page 367) into a single column with variable name Rate.
• Select Stat: Basic Statistics : 1-Sample t.
• In the “1-Sample t (Test and Confidence Interval)” dialog box, select the “Samples in columns” option.
• Select the variable name Rate into the “Samples in columns” window.
• Place a checkmark in the “Perform hypothesis test” checkbox.
• Enter the hypothesized mean (here 18.8) into the “Hypothesized mean” window.
• Click the Options… button, select the desired alternative (in this case “less than”) from the Alternative drop-down menu, and click OK in the “1-Sample t-Options” dialog box.
• To produce a boxplot of the data with a graphical representation of the hypothesis test, click the Graphs… button in the “1-Sample t (Test and Confidence Interval)” dialog box, check the “Boxplot of data” checkbox, and click OK in the “1-Sample t—Graphs” dialog box.
• Click OK in the “1-Sample t (Test and Confidence Interval)” dialog box.
• The confidence interval is given in the Session window, and the boxplot is displayed in a graphics window.
A “1-Sample Z” test is also available in MINITAB under Basic Statistics. It requires a user-specified value of the population standard deviation, which is rarely known.