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,Essentials of Biostatistics in Public Health, Fourth Edition
Lisa M. Sullivan
End-of-Chapter Answers
CHAPTER 2
1. An investigator wants to assess whether smoking is a risk factor for pancreatic cancer.
Electronic medical records at a local hospital will be used to identify 50 patients with
pancreatic cancer. One hundred patients who are similar but free of pancreatic cancer will
also be selected. Each participant’s medical record will be analyzed for smoking history.
Identify the type of study proposed and indicate its specific strengths and weaknesses.
Answer:
The study is a case-control study. Patients with pancreatic cancer are considered cases
and patients free of cancer are controls. Strengths of the design include cost and time
efficiency to identify a sufficient number of cases for analysis. Weaknesses include
generalizability (study participants were all patients at one hospital) and ascertainment of
exposure status (smoking). Exposure data will be collected from medical records, which
may not have smoking recorded accurately.
2. What is the most likely source of bias in the study described in Problem 1?
Answer:
The most likely source of bias is misclassification bias, particularly with regard to
classification of smoking status (exposure) because smoking information will be
collected from the medical record.
3. An investigator wants to assess whether the use of a specific medication given to infants
born prematurely is associated with developmental delay. Fifty infants who were given
the medication and 50 comparison infants who were also born prematurely but not given
the medication will be selected for the analysis. Each infant will undergo extensive
testing at age 2 for various aspects of development. Identify the type of study proposed
Copyright © 2023 by Jones & Bartlett Learning, LLC, an Ascend Learning Company 1
,Essentials of Biostatistics in Public Health, Fourth Edition
Lisa M. Sullivan
End-of-Chapter Answers
and indicate its specific strengths and weaknesses.
Answer:
The study is a cohort study of children born prematurely. The cohort will be designed to
include children who were given (exposed) and not given (unexposed) a specific
medication after birth. The strengths of the study are its prospective nature, which will
allow investigators to estimate incidence of developmental delay in the two comparison
groups and also to assess the temporal relationship between exposure and outcome. The
major weakness of the study is the possibility of confounding. There may be other
exposures, other than the medication, that are not measured that relate to developmental
delay.
4. Is bias or confounding more of an issue in the study described in Problem 3? Give an
example of a potential source of bias and a potential confounding factor.
Answer:
Confounding is the major issue in this cohort study. Potential confounding factors include
other medical treatments for prematurity and specific aspects of infant care (e.g., family,
environmental factors). Bias is less of an issue, but misclassification bias could be an
issue. If persons assessing the outcome (developmental delay) are aware of exposure
status, they might differentially measure outcome status. Selection bias could also be an
issue depending on the inclusion and exclusion criteria used to select participants who
were exposed and not exposed to the medication.
5. A study is planned to assess the effect of a new surgical intervention for gallbladder
disease. One hundred patients with gallbladder disease will be randomly assigned to
receive either the new surgical intervention or the standard surgical intervention. The
Copyright © 2023 by Jones & Bartlett Learning, LLC, an Ascend Learning Company 2
, Essentials of Biostatistics in Public Health, Fourth Edition
Lisa M. Sullivan
End-of-Chapter Answers
efficacy of the new surgical intervention will be measured by the time a patient takes to
return to normal activities, recorded in days. Identify the type of study proposed and
indicate its specific strengths and weaknesses.
Answer:
The study is a randomized controlled trial or a clinical trial. The strengths of the study
include randomization, which should minimize confounding. Thus, any observed
differences in return to normal activities should be attributable to treatment. One
weakness is generalizability. Details are not provided in terms of the number of centers
involved: Multiple centers would promote generalizability. Clinical trials are often also
criticized for being too narrow, specifically in terms of the patient eligibility criteria.
6. An investigator wants to assess the association between caffeine consumption and
impaired glucose tolerance, a precursor to diabetes. A study is planned to include 70
participants. Each participant will be surveyed with regard to their daily caffeine
consumption. In addition, each participant will submit a blood sample that will be used to
measure glucose level. Identify the type of study proposed and indicate its specific
strengths and weaknesses.
Answer:
The study is a cross-sectional survey. The strength of the study is that it will allow for
estimation of the prevalence and extent of caffeine consumption and impaired glucose
tolerance at a point in time. The weaknesses include inability to assess a temporal
relationship and potential for nonresponse (some participants may refuse to provide a
blood sample), limiting generalizability. Finally, the inferences that can be made from
this study are associational and limited to the time of the study only.
Copyright © 2023 by Jones & Bartlett Learning, LLC, an Ascend Learning Company 3
We have all what you need with best price,
Only find what you need and make payment and get your order, Or email us with full name
with your request.
Our email:
Our websites:
Nursing-pub.com
testbanks-store.com
,Essentials of Biostatistics in Public Health, Fourth Edition
Lisa M. Sullivan
End-of-Chapter Answers
CHAPTER 2
1. An investigator wants to assess whether smoking is a risk factor for pancreatic cancer.
Electronic medical records at a local hospital will be used to identify 50 patients with
pancreatic cancer. One hundred patients who are similar but free of pancreatic cancer will
also be selected. Each participant’s medical record will be analyzed for smoking history.
Identify the type of study proposed and indicate its specific strengths and weaknesses.
Answer:
The study is a case-control study. Patients with pancreatic cancer are considered cases
and patients free of cancer are controls. Strengths of the design include cost and time
efficiency to identify a sufficient number of cases for analysis. Weaknesses include
generalizability (study participants were all patients at one hospital) and ascertainment of
exposure status (smoking). Exposure data will be collected from medical records, which
may not have smoking recorded accurately.
2. What is the most likely source of bias in the study described in Problem 1?
Answer:
The most likely source of bias is misclassification bias, particularly with regard to
classification of smoking status (exposure) because smoking information will be
collected from the medical record.
3. An investigator wants to assess whether the use of a specific medication given to infants
born prematurely is associated with developmental delay. Fifty infants who were given
the medication and 50 comparison infants who were also born prematurely but not given
the medication will be selected for the analysis. Each infant will undergo extensive
testing at age 2 for various aspects of development. Identify the type of study proposed
Copyright © 2023 by Jones & Bartlett Learning, LLC, an Ascend Learning Company 1
,Essentials of Biostatistics in Public Health, Fourth Edition
Lisa M. Sullivan
End-of-Chapter Answers
and indicate its specific strengths and weaknesses.
Answer:
The study is a cohort study of children born prematurely. The cohort will be designed to
include children who were given (exposed) and not given (unexposed) a specific
medication after birth. The strengths of the study are its prospective nature, which will
allow investigators to estimate incidence of developmental delay in the two comparison
groups and also to assess the temporal relationship between exposure and outcome. The
major weakness of the study is the possibility of confounding. There may be other
exposures, other than the medication, that are not measured that relate to developmental
delay.
4. Is bias or confounding more of an issue in the study described in Problem 3? Give an
example of a potential source of bias and a potential confounding factor.
Answer:
Confounding is the major issue in this cohort study. Potential confounding factors include
other medical treatments for prematurity and specific aspects of infant care (e.g., family,
environmental factors). Bias is less of an issue, but misclassification bias could be an
issue. If persons assessing the outcome (developmental delay) are aware of exposure
status, they might differentially measure outcome status. Selection bias could also be an
issue depending on the inclusion and exclusion criteria used to select participants who
were exposed and not exposed to the medication.
5. A study is planned to assess the effect of a new surgical intervention for gallbladder
disease. One hundred patients with gallbladder disease will be randomly assigned to
receive either the new surgical intervention or the standard surgical intervention. The
Copyright © 2023 by Jones & Bartlett Learning, LLC, an Ascend Learning Company 2
, Essentials of Biostatistics in Public Health, Fourth Edition
Lisa M. Sullivan
End-of-Chapter Answers
efficacy of the new surgical intervention will be measured by the time a patient takes to
return to normal activities, recorded in days. Identify the type of study proposed and
indicate its specific strengths and weaknesses.
Answer:
The study is a randomized controlled trial or a clinical trial. The strengths of the study
include randomization, which should minimize confounding. Thus, any observed
differences in return to normal activities should be attributable to treatment. One
weakness is generalizability. Details are not provided in terms of the number of centers
involved: Multiple centers would promote generalizability. Clinical trials are often also
criticized for being too narrow, specifically in terms of the patient eligibility criteria.
6. An investigator wants to assess the association between caffeine consumption and
impaired glucose tolerance, a precursor to diabetes. A study is planned to include 70
participants. Each participant will be surveyed with regard to their daily caffeine
consumption. In addition, each participant will submit a blood sample that will be used to
measure glucose level. Identify the type of study proposed and indicate its specific
strengths and weaknesses.
Answer:
The study is a cross-sectional survey. The strength of the study is that it will allow for
estimation of the prevalence and extent of caffeine consumption and impaired glucose
tolerance at a point in time. The weaknesses include inability to assess a temporal
relationship and potential for nonresponse (some participants may refuse to provide a
blood sample), limiting generalizability. Finally, the inferences that can be made from
this study are associational and limited to the time of the study only.
Copyright © 2023 by Jones & Bartlett Learning, LLC, an Ascend Learning Company 3
