MPH501 2020 January Module 5 Quiz Latest

MPH501 Quantitative Methods for Public Health Application

Module 5 Quiz

Question 1Recent 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 2A clinical trial is planned to compare an experimental medication designed to lower blood pressure to a placebo.  Before starting the trial, a pilot study is conducted involving 7 participants.  The objective of the study is to assess how systolic blood pressure changes over time untreated.  Systolic blood pressures are measured at baseline and again 4 weeks later.  Is there a statistically significant difference in blood pressures over time?  Run the test at a 5% level of significance.

Baseline         120    145     130   160    152    143   126  

4 Weeks         122    142    135    158    155    140   130  

Difference     -2       3        -5       2        -3       3        -4      []Differences = -6

Difference2   4        9        25      4        9        9        16      []Differences2 = 76

Question 3The 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.

Question 4An 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.