MPH501 Module 4 Exercise Latest 2020 January

MPH501 Quantitative Methods for Public Health Application

Module 4 Exercise

Question 1 A study is run to estimate the mean total cholesterol level in children 2-6 years of age.  A sample of 9 participants is selected and their total cholesterol levels are measured as follows.

185      225      240      196      175      180      194      147      223

Generate a 95% confidence interval for the true mean total cholesterol levels in adults with a history of hypertension.

X	X2
185	34,225
225	50,625
240	57,600
196	38,416
175	30,625
180	32,400
194	37,636
147	21,609
223	49,729
1,765	352,865

Question 2 The main trial 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.

Generate a 95% confidence interval for the difference in mean systolic blood pressures between groups.

Question 3 The following data are collected as part of a study of coffee consumption among undergraduate students.  The following reflect cups per day consumed:

3          4          6          8          2          1          0          2

X	X2
3	9
4	16
6	36
8	64
2	4
1	1
0	0
2	4
26	134

 

Compute the sample mean

Compute the sample standard deviation

Construct a 95% confidence interval for the mean number of cups of coffee consumed among all undergraduates.

Question 4 The following table displays descriptive statistics on the participants involved in a study.

Characteristic	Experimental Medication (n=100)	Placebo (n=100)
Mean (SD) Age, years	47.2 (4.3)	46.1 (5.1)
% Males	46%	58%
Mean (SD) Educational Level, years	13.1 (2.9)	14.2 (3.1)
Mean (SD) Annual Income, $000s	$36.560 ($1,054)	$37.470 ($998)
Mean Body Mass Index	24.7 (2.7)	25.1 (2.4)

 

Generate a 95% confidence interval for the mean age among participants assigned to the placebo.

Generate a 95% confidence interval for the difference in mean ages in participants assigned to the experimental versus the placebo groups.

Generate a 95% confidence interval for the difference in mean body mass index in participants assigned to the experimental versus the placebo groups.

Question 5 A crossover trial is conducted to compare an experimental medication for migraine headaches to a currently available medication.  A total of 50 patients are enrolled in the study and each patient receives both treatments.  The outcome is the time, in minutes, until the headache pain resolves.  Following each treatment, patient’s record the time it takes until pain is resolved.  Treatments are assigned in random order (i.e., some patients receive the currently available medication first and then the experimental medication and others receive the experimental medication first and then the currently available medication).  The mean difference in times between the experimental and currently available medication is -9.4 minutes, with a standard deviation of 2.8 minutes.  Construct a 95% confidence interval for the mean difference in times between the experimental and currently available medication.

Question 6 A clinical trial is run to assess the efficacy of a new pacemaker device in patients with atrial fibrillation (AF).  Two hundred participants are randomized to receive the new pacemaker or a currently available pacemaker.  There are two primary outcomes of interest – the number of days in a three month period with an atrial fibrillation event and hospitalization for atrial fibrillation over the three month follow-up period.  Data on baseline characteristics and the outcomes are shown below.

Baseline Characteristics	New Pacemaker (n=100)	Available Pacemaker (n=100)
Mean (SD) Age, years	67.3 (5.9)	66.9 (5.6)
% Male	48%	52%
Outcomes
Mean (SD) Number of days with AF event	8.4 (3.2)	14.9 (3.9)
% Hospitalized for AF	4%	9%

 

Compute a 95% confidence interval for the difference in mean number of days with an AF event between participants receiving the new pacemaker as compared to the available pacemaker.

Compute a 95% confidence interval for the mean number of days with an AF event among participants receiving the new pacemaker.