MPH501 All Quizzes Latest 2020 January

MPH501 Quantitative Methods for Public Health Application

Module 1 Quiz

Question 1A study is planned to assess the effect of a new surgical intervention for kidney stones. One hundred-fourteen patients with kidney stones will be randomly assigned to receive either the new surgical intervention or the standard surgical intervention.  The efficacy of the new surgical intervention will be measured by the time it takes a patient to return to normal  activities, measured in days.  Identify the type of study proposed and indicate its specific strengths and weaknesses.

Question 2An investigator wants to assess whether increased levels of pesticide exposure is a risk factor for colon cancer. Electronic medical records at a local hospital will be used to identify 74 patients with colon cancer. One hundred eleven patients who are similar but free of colon cancer will also be selected.  Each participant’s medical record will be analyzed for pesticide exposure history.  Identify the type of study proposed and indicate its specific strengths and weaknesses.

Question 3Describe at least two sources of bias in the study described in Question 3.

Question 4Which of the below is not the most common qualitative method?  

Surveys

Participant observation

In-depth interviews

Focus groups

Question 5What type of data is generated from qualitative research methods? Select all that apply.

Field Notes

Audio (or video) recordings

Transcripts

Questionnaire data

 

MPH501 Quantitative Methods for Public Health Application

Module 2 Quiz

Question 1The following are baby height measurements, in cm, for a sample of infants participating in a study of infant health:

28        30        41        48        29        48        62        49        51        39

a.          Compute the sample mean.

b.          Compute the sample standard deviation.

c.           Compute the median.

d.          Compute the first and third quartiles.

e.          Which measure, the mean or median, is a better measure of a typical value?  Justify.

f.           Which measure, the standard deviation or the interquartile range, is a better measure of dispersion?  Justify.

Question 2A pilot study is run to investigate the feasibility of recruiting pregnant women into a study of risk factors for preterm delivery. Women are invited to participate at their first clinical visit for prenatal care.  The following represent the gestational ages in weeks of women who consent to participate in the study.

11        14        21        22        9          10        13        18      

X           X2

11         121

14         196

21         441

22         484

9           81

10         100

13         169

18         324

118       1916

a.          Compute the sample mean gestational age.

b.          Compute the sample standard deviation of gestational age.

c.           Compute the median gestational age

d.          What proportion of the sample enroll in first trimester of pregnancy (i.e., between 1-13 weeks, inclusive, of pregnancy)?

Question 3A prospective cohort study is run to estimate the incidence of stroke in persons 55 years of age and older.  All participants are free of stroke at study start.  Each participant is followed for a maximum of 5 years.  The data are summarized below.

             Number of Strokes          Number of Stroke Free Person-Years

 Men (n=125)     9          478

 Women (n=200)             21        974

a.          What is the annual incidence rate of stroke in men?

b.          What is the annual incidence rate of stroke in women?

c.           What is the annual incidence rate of stroke (men and women combined)?

Question 4A clinical trial is run to assess the efficacy of a new drug to reduce high blood pressure.  Patients with a diagnosis of hypertension (high blood pressure) are recruited to participate in the trial and randomized to receive either the new drug or placebo.  Participants take the assigned drug for 12 weeks and their blood pressure status is recorded.  At the end of the trial, participants are classified as still having hypertension or not.  The data are shown below:

Group   Number Randomized      Number Free of Hypertension at 12 Weeks

Placebo 50         6

New Drug          50         14

a.          What is the prevalence of hypertension at the start of the trial?

b.          What is the prevalence of hypertension at the end of the trial?

c.           Estimate the relative risk comparing the proportions who are free of hypertension at 12 weeks between groups.

 

MPH501 Quantitative Methods for Public Health Application

Module 3 Quiz

Question 1Diastolic blood pressures are assumed to follow a normal distribution with a mean of 85 and a standard deviation of 12.

a.          What proportion of people have diastolic blood pressure less than 90?

b.          What proportion have diastolic blood pressures between 80 and 90?

Question 2Consider the data described in Problem 1.

a.          If a sample of 15 participants are sampled, what is the probability that their mean diastolic blood pressure exceeds 90?

b.          Describe a study you could conduct on this population using one of the qualitative data collection methods you’ve learned about previously.

Question 3The following table cross classifies women in the study by their body mass index (BMI) at 16 weeks gestation and whether they had preterm delivery.

             BMI < 30            BMI 30-34.9       BMI 35+

Preterm             320       80         120

Full Term           4700     480       300

a.          What is the probability that a woman delivers preterm?

b.          What is the probability a women has BMI <30 and delivers preterm?

c.           What proportion of women with BMI 35+ deliver preterm?

d.          Are BMI and preterm delivery independent?  Justify.

Question 4The following table displays the number of children in a local town classified as normal weight, overweight and obese by year in school.

             Normal Weight  Overweight        Obese   Total

Elementary        50         120       80         250

Middle  30         45         45         120

Junior High        50         50         40         140

High School        30         85         85         200

Total     160       300       250       710

a.          What proportion of the children are obese?

b.          What proportion of the normal weight children are in high school?

Question 5The following table summarizes data collected in a study to evaluate a new screening test for ovarian cancer.  A total of 200 women were involved in the study – 50 had ovarian cancer and 150 did not.  The results are tabulated below.

                          Ovarian Cancer Free of Ovarian Cancer

Screening Test   Positive 28         23

             Negative            22         127

                          50         150

a.          Find the sensitivity of the screening test.

b.          Find the false positive fraction of the screening test.

 

MPH501 Quantitative Methods for Public Health Application

Module 4 Quiz

Question 1 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 2 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.

Question 3 The following table shows the numbers of patients classified as underweight, normal weight, overweight and obese according to their diabetes status.

	Underweight	Normal Weight	Overweight	Obese
Diabetes	8	34	43	65
No Diabetes	12	85	40	93

If a patient is selected at random,

What is the probability that they are overweight?                            

What is the probability that they are obese and diabetic?                

What proportion of the diabetics are obese?                                    

What proportion of normal weight patients are not diabetic?          

What proportion of patients are normal weight or underweight?   

Question 4 An investigator wants to test whether exposure to second-hand smoke before 1 year of life is associated with development of childhood asthma (defined as asthma diagnosed before 5 years of age).  Give two possible study designs and indicate the pros and cons of each.  Then, provide your recommendation for the most efficient design.

Question 5 A study is run to estimate the incidence of atrial fibrillation (AF) in men and women over the age of 60.  Development of atrial fibrillation was monitored over a 10 year follow-up period.  The data are summarized below.

	Developed AF		Did not Develop AF
Men	120		6453
Women	86		7074
Developed AF		Did not Develop AF
Men		120		6453
Women		86		7074

Compute the cumulative incidence of AF in men and in women

Compute the relative risk of AF incidence comparing men to women

Compute the odds ratio of AF incidence comparing men and women

Question 6 The following data were collected in a survey of 8th graders and summarize their cell phone status.

No cell phone	Conventional cell phone user	Smart phone user
Boys	22	60	45
Girls	34	88	27

 

What proportion of the 8th graders have cell phones?

What proportion of the boys do not have cell phones?

Is  ownership of a cell phone independent of sex?  Justify your answer.

What proportion of smart phone users are boys? 

Question 7 The following table shows the results of a screening test hypothesized to detect persons at risk for side effects of a new cosmetic surgery.

Side effects present	Side effects absent
Screen positive	20	4
Screen negative	105	250

Compute the sensitivity of the test 

Compute the specificity of the test

Compute the false positive fraction

Compute the false negative fraction

Question 8 A random sample of eight adults aged 30 years were asked how much they spent on medical costs in the year 2009.  The following data were measured.

300      140      5600    520      470      700      640      1200

Compute the sample mean

Compute the sample standard deviation

Compute the sample median

Compute the first and third quartiles

Question 9 Four hundred melanoma patients were diagnosed according to the type of skin cancer and the location of the skin cancer.  This data is presented below.

Location
Type	Head and Neck	Trunk	Extremities	Total
Hutchinson’s Melanomic Freckle	22	2	10	34
Indeterminate	11	17	28	56
Nodular	19	33	73	125
Superficial Spreading Melanoma	16	54	115	185
Total	68	106	226	400

 What proportion of patients had Superficial Spreading Melanoma? 

Of patients with a skin cancer on the Trunk, what proportion had a nodular skin cancer?

What proportion of patients had a Hutchinson’s Melanomic Freckle on the extremities?

 Is type of skin cancer independent of location?  Justify your answer.

Question 10The gestation period for human births can be taken as normally distributed with a mean of 266 days and a standard deviation of 16 days.

What is the probability that a randomly chosen baby had a gestation period of more than 280 days?

If a gestation period if 276 days, what percentile among human births is this?

 

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.

 

MPH501 Quantitative Methods for Public Health Application

Module 6 Quiz

Question 1Some scientists believe that alcoholism is linked to social isolation.  One measure of social isolation is marital status.  A study of 280 adults is conducted and each participant is classified as not alcoholic, diagnosed alcoholic or undiagnosed alcoholic, and categorized by marital status.  Is there significant evidence of an association?  Run the appropriate test at a 5% level of significance.

Diagnosed Alcoholic	Undiagnosed Alcoholic	Not Alcoholic
Married	21	37	58
Not Married	59	63	42

Question 2Suppose a hypertension trial is mounted and 18 participants are randomly assigned to one of the comparison treatments.  Each participant takes the assigned medication and their systolic blood pressure (SBP) is recorded after 6 months on the assigned treatment.  The data are as follows.

Standard Treatment	Placebo	New Treatment
124	134	114
111	143	117
133	148	121
125	142	124
128	150	122
115	160	128

Is there a difference in mean SBP among treatments?  Run the appropriate test at []=0.05. 

Question 3A clinical trial is conducted to compare an experimental medication to placebo to reduce the symptoms of asthma.  Two hundred participants are enrolled in the study and randomized to receive either the experimental medication or placebo.  The primary outcome is self-reported reduction of symptoms.  The data are recorded as follows.

Change in Symptoms
Treatment	Much Worse	Worse	No change	Better	Much Better
Experimental	10	17	35	28	10
Placebo	12	25	42	12	9

 

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

Question 4The following data was collected in a clinical trial evaluating a new medication designed to improve wound healing in trauma patients.  The new compound is compared against a placebo.  After treatment for 10 days with the new compound or placebo the extent of wound healing is measured and the data are shown below.

Percent Wound Healing
Treatment	0-25%	26-50%	51-75%	76-100%
New psoriasis medication (n=125)	15	37	32	41
Placebo (n=125)	36	45	34	10

 

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.

 

MPH501 Quantitative Methods for Public Health Application

Module 7 Quiz

Question 1 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 i