A clinical trial is run to evaluate the efficacy

A clinical trial is run 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 0-100 with higher scores indicative of more pain.  Data on the primary outcome are shown below.

Sample Size

Mean Pain Score

Standard Deviation of Pain Score

New Medication

60

30.31

7.52

Standard Medication

60

53.85

7.44

Because procedures can be more complicated in older patients, the investigators are concerned about confounding by age.  For analysis, patients are classified into two age groups, less than 65 and 65 years of age and older.  The data are shown below.

Age < 65 Years Sample Size Mean Pain Score Standard Deviation of Pain Score New Medication 40 25.30 2.46 Standard Medication 25 45.51 1.83 Total: Age < 65 Years 65 33.07 10.16 Age 65+ Years Sample Size Mean Pain Score Standard Deviation of Pain Score New Medication 20 40.33 2.16 Standard Medication 35 59.80 2.49 Total: Age 65+ 55 52.72 9.74 1. 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 .05.  (Ignore age in this analysis.)

A clinical trial is run to evaluate the efficacy

A clinical trial is run 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 0-100 with higher scores indicative of more pain.  Data on the primary outcome are shown below.

Sample Size

Mean Pain Score

Standard Deviation of Pain Score

New Medication

60

30.31

7.52

Standard Medication

60

53.85

7.44

Because procedures can be more complicated in older patients, the investigators are concerned about confounding by age.  For analysis, patients are classified into two age groups, less than 65 and 65 years of age and older.  The data are shown below.

Age < 65 Years Sample Size Mean Pain Score Standard Deviation of Pain Score New Medication 40 25.30 2.46 Standard Medication 25 45.51 1.83 Total: Age < 65 Years 65 33.07 10.16 Age 65+ Years Sample Size Mean Pain Score Standard Deviation of Pain Score New Medication 20 40.33 2.16 Standard Medication 35 59.80 2.49 Total: Age 65+ 55 52.72 9.74 1. 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 .05.  (Ignore age in this analysis.)

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