MPH501 2020 January Module 5 Exercise Latest

MPH501 Quantitative Methods for Public Health Application

Module 5 Exercise

Question 1 An investigator hypothesizes that cholesterol levels in children might be affected by educating their parents on proper nutrition and exercise.  A sample of 40 families with a child between the ages of 10-15 who has been diagnosed with high cholesterol agree to participate in the study.  All parents are provided educational information on nutrition and exercise.  After following the prescribed program, their child’s total cholesterol level is measured.  The children’s mean cholesterol level is 175 with a standard deviation of 19.5.  Is there significant evidence of a reduction in total cholesterol in the children?  Run the appropriate test at the 5% level of significance and assume that the null value for total cholesterol is 191.

Question 2 The main trial in Problem 7 is conducted and involves a total of 200 patients.  Patients are enrolled and randomized to receive either the experimental medication or the placebo.  The data shown below are data collected at the end of the study after 6 weeks on the assigned treatment.

a.          Test if there is a significant difference in mean systolic blood pressures between groups using []=0.05.

Question 3Suppose a secondary outcome is recorded in the trial described in Problem 10 reflecting asthma symptom severity measured on a scale of 0-100 with higher scores indicating more severe symptoms.  In the participants who receive the experimental medication the mean symptom score is 74 with a standard deviation of 5.6 and in the placebo group the mean symptom score is 85 with a standard deviation of 6.0.  Is there a significant difference in mean symptom scores between groups?  Run the appropriate test at a 5% level of significance.

Question 4 Recent recommendations suggest 60 minutes of physical activity per day.  A sample of 50 adults in a study of cardiovascular risk factors report exercising a mean of 38 minutes per day with a standard deviation of 19 minutes.  Based on the sample data, is the physical activity significantly less than recommended?  Run the appropriate test at a 5% level of significance.

Question 5 A study is conducted to compare mean cholesterol levels for individuals following a low carbohydrate diet for at least 6 months to individuals following a conventional (low-fat, low calorie) diet for at least 6 months.  The data are summarized below:

Diet Program     Sample Size       Mean Cholesterol           Std Dev Cholesterol

Low Carbohydrate          50         225.4    24.5

Conventional     75         203.8    21.6

Test if there is a significant difference in mean cholesterol levels between the diet programs using a 5% level of significance.

Question 6 The mean lifetime for cardiac stents is 8.9 years.  A medical device company has implemented some improvements in the manufacturing process and hypothesizes that the lifetime is now longer.  A study of 40 new devices reveals a mean lifetime of 9.7 years with a standard deviation of 3.4 years.  Is there statistical evidence of a prolonged lifetime of the stents?  Run the test at a 5% level of significance.