Refer to Exercise 7.39 and the Analytical Chemistry (Dec. 15, 2009) study in which scientists used high-performance

Question:

Refer to Exercise 7.39 and the Analytical Chemistry (Dec. 15, 2009) study in which scientists used high-performance liquid chromatography to determine the amount of drug in a tablet. Recall that 25 tablets were produced at each of two different, independent sites, and drug concentration (measured as a percentage) was determined for each tablet. These data are reproduced in the accompanying table. In Exercise 7.39 you used a 95% confidence interval to determine whether there is any difference between the mean drug concentration in tablets produced at the two sites. Now analyze the data using a statistical test of hypothesis at α = .05. (See the accompanying MINITAB printout.) Do the inferences drawn from the test of hypothesis and confidence interval agree?

Data form Exercise 7.39

Refer to Exercise 5.45 and the Analytical Chemistry (Dec. 15, 2009) study in which scientists used high-performance liquid chromatography to determine the amount of drug in a tablet. Twenty-five tablets were produced at each of two different, independent sites. Drug concentrations (measured as a percentage) for the tablets produced at the two sites are listed in the accompanying table. The scientists want to know whether there is any difference between the mean drug concentration in tablets produced at Site 1 and the corresponding mean at Site 2. Use the MINITAB printout below to help the scientists draw a conclusion.

Data from Exercise 5.45

Scientists at GlaxoSmithKline Medicines Research Center used high-performance liquid chromatography (HPLC) to determine the amount of drug in a tablet produced by the company. (Analytical Chemistry, Dec. 15, 2009.) Drug concentrations (measured as a percentage) for 50 randomly selected tablets are listed in the accompanying table and saved in the DRUGCON file.