Question: A clinical trial is conducted to evaluate the efficacy of a new medication to relieve pain in patients undergoing total knee replacement surgery. In the trial, patients are randomly assigned to receive either the new medication or the standard medication. After receiving the assigned medication, patients are asked to report their pain on a scale of 0 to 100, with higher scores indicative of more pain. Data on the primary outcome are shown in Table 9-15. Because procedures can be more complicated in older patients, the investigators were concerned about confounding by age. For analysis, patients were classified into two age groups, less than 65 years old and 65 years of age and older. The data are shown in Table 9-16. Is there a statistically significant difference in mean pain scores between patients assigned to the new medication as compared to the standard medication? Run the appropriate test at a = 0.05. (Ignore age in this analysis.)