474 CHAPTER 9 Inferences from Two Samples YOUR TURN. Do Part (b) of Exercise 5 “Measured and Reported Weights.” INTERPRETATION We have 90% confidence that the limits of -2.05 lb and 4.90 lb contain the true value of the mean of the “measured – reported” differences. In the long run, 90% of such samples will lead to confidence interval limits that actually do contain the true population mean of those differences. See that the confidence interval includes the value of 0 lb, so it is very possible that the mean of the differences is equal to 0 lb, indicating that there is no significant difference between measured weights and reported weights. Remember, this conclusion is based on the very small sample included in Table 9-2. Alternative Methods: Resampling Methods of Bootstrapping and Randomization The claim that the measured weights of males tend to be higher than the reported weights can be tested by using the resampling methods of bootstrapping and randomization. See Section 9-5 “Resampling: Using Technology for Inferences.” Inferences with Two Means: Matched Pairs Access tech supplements, videos, and data sets at www.TriolaStats.com TECH CENTER Statdisk Requires paired sample data entered in columns. Hypothesis Testing 1. Click Analysis in the top menu. 2. Select Hypothesis Testing from the dropdown menu and Mean Matched Pairs from the submenu. 3. Select the desired format for Alternative Hypothesis, enter the significance level, and select the data columns to compare. 4. Click Evaluate. Confidence Intervals 1. Click Analysis in the top menu. 2. Select Confidence Intervals from the dropdown menu and Mean Matched Pairs from the submenu. 3. Enter the desired confidence level and select the data columns to compare. 4. Click Evaluate. StatCrunch Requires paired sample data entered in columns. 1. Click Stat in the top menu. 2. Select T Stats from the dropdown menu, then select Paired from the submenu. 3. Select the columns containing paired sample data. 4. Hypothesis Testing: Select Hypothesis test for MD = M1 − M2. For hypothesized difference 1H02 enter 0 and select the desired format for the alternative hypothesis 1HA2. Confidence Intervals: Select Confidence interval for MD = M1 − M2 and enter the confidence level. 5. Click Compute! Minitab Requires paired sample data entered in columns. 1. Click Stat in the top menu. 2. Select Basic Statistics from the dropdown menu and select Paired t from the submenu. 3. Select Each sample is in a column from the dropdown menu and select the desired data columns. 4. Click the Options button and enter the confidence level. Enter 0 for the Hypothesized difference and select the desired format for the Alternative hypothesis. 5. Click OK twice.
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