MPH501 2020 January Module 6 Exercise Latest

MPH501 Quantitative Methods for Public Health Application

Module 6 Exercise

Question 1 The following data was collected in a clinical trial evaluating a new compound designed to improve wound healing in trauma patients.  The new compound is compared against a placebo.  After treatment for 5 days with the new compound or placebo the extent of wound healing is measured and the data are shown below.

Is there a difference in the extent of wound healing by treatment?  (Hint:  Are treatment and the percent wound healing independent?)  Run the appropriate test at a 5% level of significance.

Question 2The following data were collected in an experiment designed to investigate the impact of different positions of the mother during ultrasound on fetal heart rate.  Fetal heart rate is measured by ultrasound in beats per minute.  The study includes 20 women who are assigned to one position and have the fetal heart rate measured in that position.  Each woman is between 28-32 weeks gestation.  The data are shown below.

Is there a significant difference in mean fetal heart rates by position?  Run the test at a 5% level of significance.

Question 3In this study patients were recruited from 3 different clinical sites.  Use the following data to test if there is a difference in the proportions of hypertensive patients across clinical sites.

Question 4 Suppose more detail is actually recorded in the primary outcome in the clinical trial described in Problem 10.  The data are recorded as follows.

Is there a difference in change in symptoms by treatment group?  Run the appropriate test at a 5% level of significance.

Question 5An investigator wants to estimate caffeine consumption in high school students. How many students would be required to ensure that a 95% confidence interval estimate for the mean caffeine intake (measured in mg) is within 15 mg of the true mean? Assume that the standard deviation in caffeine intake is 68 mg.

Question 6 A crossover trial is planned to evaluate the impact of an educational intervention program to reduce alcohol consumption in patients determined to be at risk for alcohol problems. The plan is to measure alcohol consumption (the number of drinks on a typical drinking day) before the intervention and then again after participants complete the educational intervention program. How many participants would be required to ensure that a 95% confidence interval for the mean difference in the number of drinks is within 2 drinks of the true mean difference? Assume that the standard deviation of the difference in the mean number of drinks is 6.7 drinks and that 20% of the participants will drop out over the course of follow up.