Preventive Medicine: Epidemiology 5
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Questions and Answers

What is the primary purpose of research design?

  • To develop a list of possible candidates for disease causes
  • To make predictions from hypotheses
  • To collect and arrange data for analysis (correct)
  • To generate hypotheses for disease causes

    • What type of research is concerned with obtaining the frequency of a disease in a certain place at a certain time?

  • Qualitative research
  • Descriptive research (correct)
  • Hypothesis generation
  • Hypothesis testing

    • What is the outcome of a research question that asks 'What caused this disease?'

  • A hypothesis testing result
  • A list of possible candidates for the causes of the disease (correct)
  • A fair, unbiased comparison between groups
  • A descriptive answer

    • What is the purpose of hypothesis generation?

    <p>To develop a list of possible candidates for disease causes</p> Signup and view all the answers

    What is the outcome of a hypothesis testing result that does not support the hypothesis?

    <p>The hypothesis is discarded</p> Signup and view all the answers

    What is the basic function of most epidemiologic research designs?

    <p>To describe the pattern of health problems accurately</p> Signup and view all the answers

    What is the limitation of research designs?

    <p>Each design has its advantages and disadvantages</p> Signup and view all the answers

    What is the importance of data quality in research?

    <p>No research is better than the quality of the data obtained</p> Signup and view all the answers

    What is a major disadvantage of cross-sectional surveys?

    <p>They are biased towards longer-lasting and more indolent cases of diseases</p> Signup and view all the answers

    What is the primary advantage of mailed surveys?

    <p>They are relatively inexpensive</p> Signup and view all the answers

    What can repeated cross-sectional surveys be used to determine?

    <p>Changes in risk factors and disease frequency in populations over time</p> Signup and view all the answers

    What is healthy participant bias?

    <p>A bias towards participants who are more concerned about their health</p> Signup and view all the answers

    What can be inferred from a high IgG titer without an IgM titer of antibody to a particular infectious agent?

    <p>The study participant has been infected in the distant past</p> Signup and view all the answers

    What is the primary purpose of collecting acute and convalescent sera in infectious disease epidemiology?

    <p>To provide evidence about when and in whom an infection has occurred</p> Signup and view all the answers

    What is a limitation of cross-sectional surveys in determining the temporal relationship of a presumed cause and effect?

    <p>Data on exposure to risk factors and the presence or absence of disease are collected simultaneously</p> Signup and view all the answers

    What is an advantage of cross-sectional surveys?

    <p>They are useful for determining the prevalence of risk factors and the frequency of prevalent cases of certain diseases</p> Signup and view all the answers

    What is the purpose of collecting two serum samples separated by a short interval in infectious disease epidemiology?

    <p>To prove a recent acute infection</p> Signup and view all the answers

    What is the primary function of a good epidemiologic research design?

    <p>To allow a comparison of a variable between two or more groups</p> Signup and view all the answers

    What is a disadvantage of cross-sectional surveys in infectious disease epidemiology?

    <p>They are biased towards longer-lasting and more indolent cases of diseases</p> Signup and view all the answers

    Which type of research design is usually the best for testing hypotheses?

    <p>Randomized clinical trial</p> Signup and view all the answers

    What is the main difference between observational and experimental study designs?

    <p>The level of control the investigator has over the assignment of participants</p> Signup and view all the answers

    What is the purpose of qualitative research?

    <p>To provide rich, narrative information</p> Signup and view all the answers

    What is a characteristic of descriptive observational studies?

    <p>No hypotheses are specified in advance</p> Signup and view all the answers

    What is the main limitation of telephone surveys or e-mail questionnaires?

    <p>They have many nonresponders and refusals</p> Signup and view all the answers

    What is the purpose of analytic observational studies?

    <p>To measure differences between groups</p> Signup and view all the answers

    What is an advantage of qualitative research?

    <p>It provides rich, narrative information</p> Signup and view all the answers

    What is the purpose of a cross-sectional survey?

    <p>To survey a population at a single point in time</p> Signup and view all the answers

    What is a characteristic of experimental study designs?

    <p>The investigator has more control over the assignment of participants</p> Signup and view all the answers

    What is the unit of analysis in ecological studies?

    <p>Populations</p> Signup and view all the answers

    What can cross-sectional ecological studies be used for?

    <p>Suggesting hypotheses</p> Signup and view all the answers

    What is the weakness in cross-sectional ecological surveys?

    <p>Ecological fallacy</p> Signup and view all the answers

    What was found to be associated with lower rates of dental caries in children?

    <p>High levels of natural fluoridation</p> Signup and view all the answers

    What is the purpose of longitudinal ecological studies?

    <p>To determine the impact of changes in society on disease rates</p> Signup and view all the answers

    What was the result of introducing the polio vaccine in the U.S. population?

    <p>A precipitous decrease in the rate of paralytic poliomyelitis</p> Signup and view all the answers

    What is a limitation of longitudinal ecological studies?

    <p>Confounders can distort conclusions</p> Signup and view all the answers

    What is an example of a causal association suggested by longitudinal ecological studies?

    <p>Smoking and lung cancer</p> Signup and view all the answers

    In a case-control study, what is the primary factor in selecting the case and control groups?

    <p>Defined outcome, such as having a disease of interest</p> Signup and view all the answers

    What can be estimated from a case-control study?

    <p>The relative risk of the outcome</p> Signup and view all the answers

    Why are case-control studies often preferred when studying rare diseases?

    <p>They can be performed quickly and inexpensively</p> Signup and view all the answers

    What is the main difference between cohort studies and case-control studies?

    <p>Cohort studies are defined on the basis of exposure and case-control studies are defined on the basis of outcome status.</p> Signup and view all the answers

    What is the primary advantage of prospective cohort studies?

    <p>They allow for the control and standardization of data collection.</p> Signup and view all the answers

    What is the term used to describe the time relationships in a case-control study?

    <p>Simultaneous</p> Signup and view all the answers

    Why is it important to select all cases with the disease of interest in a given geographic area and time period?

    <p>To reduce bias in case selection</p> Signup and view all the answers

    What is a disadvantage of cohort studies?

    <p>They have high costs and require a long wait until results are obtained.</p> Signup and view all the answers

    What is the primary difference between a case-control study and a cross-sectional study?

    <p>The method of assembling participants</p> Signup and view all the answers

    What is the purpose of a retrospective cohort study?

    <p>To define a risk group and follow group members to see what outcomes have occurred.</p> Signup and view all the answers

    What is the term used to describe the measure of the strength of the association between the risk factor and the outcome in a case-control study?

    <p>Odds ratio</p> Signup and view all the answers

    What is an advantage of retrospective cohort studies?

    <p>They are less expensive than prospective cohort studies.</p> Signup and view all the answers

    Why are prospective cohort studies useful?

    <p>They can study multiple disease outcomes, including those not anticipated at the beginning of the study.</p> Signup and view all the answers

    What is a limitation of retrospective cohort studies?

    <p>They lack the ability to monitor and control data collection.</p> Signup and view all the answers

    What is a characteristic of prospective cohort studies?

    <p>They collect baseline data on participants and follow them for a period of time.</p> Signup and view all the answers

    What is an advantage of cohort studies?

    <p>They can study multiple disease outcomes, including those not anticipated at the beginning of the study.</p> Signup and view all the answers

    What is the main difference between a randomized controlled field trial (RCFT) and a randomized controlled clinical trial (RCCT)?

    <p>The type of intervention</p> Signup and view all the answers

    What is a disadvantage of randomized controlled field trials (RCFTs) and randomized controlled clinical trials (RCCTs)?

    <p>Results may take a long time to obtain</p> Signup and view all the answers

    What is the purpose of meta-analysis in clinical research?

    <p>To summarize the information obtained in many single studies on one topic</p> Signup and view all the answers

    What is the purpose of decision analysis in clinical research?

    <p>To show how data can inform clinical or policy decisions</p> Signup and view all the answers

    What is the purpose of cost-effectiveness analysis in clinical research?

    <p>To compare the costs and outcomes of different interventions</p> Signup and view all the answers

    What is the limitation of randomized controlled field trials (RCFTs) and randomized controlled clinical trials (RCCTs) in terms of external validity?

    <p>It may be unclear which population is actually represented by the remaining people in the trial</p> Signup and view all the answers

    What is the primary use of summary techniques in clinical preventive services?

    <p>To develop recommendations for clinical preventive services</p> Signup and view all the answers

    What is an example of a randomized controlled field trial (RCFT)?

    <p>A trial of a vaccine to prevent paralytic poliomyelitis</p> Signup and view all the answers

    What is another term for a randomized controlled field trial (RCFT)?

    <p>Community-based randomized controlled trial</p> Signup and view all the answers

    What is the purpose of postapproval surveillance in drug approvals?

    <p>To identify side effects not seen in earlier studies</p> Signup and view all the answers

    What is the term used to describe the process of looking for associations in large datasets?

    <p>Data dredging</p> Signup and view all the answers

    What is the danger of data dredging in research?

    <p>It can lead to false positive findings</p> Signup and view all the answers

    What is the purpose of a correlational study?

    <p>To develop hypotheses</p> Signup and view all the answers

    Why is it important to keep in mind the limitations of correlational studies?

    <p>Because they are limited in their ability to establish causality</p> Signup and view all the answers

    What is an example of a well-known instance of data dredging?

    <p>The association between coffee consumption and pancreatic cancer</p> Signup and view all the answers

    What is the problem that arises when looking for associations in a large dataset?

    <p>Data dredging</p> Signup and view all the answers

    Study Notes

    Functions of Research Design

    • Research is the process of answering a question that can be answered by collecting and analyzing data
    • Descriptive research involves answering questions like "What is the frequency of a disease in a certain place at a certain time?"
    • Research designs are rules that govern the process of collecting and arranging data for analysis
    • Research designs can be used to generate hypotheses, test hypotheses, or both

    Types of Research Design

    • Observational designs:
      • Qualitative studies: involve anthropologic techniques like ethnographic observation, open-ended interviews, focus groups, and key informant interviews
      • Cross-sectional surveys: study a population at a single point in time to determine the prevalence of risk factors and disease frequency
      • Cross-sectional ecological studies: relate the frequency of characteristics and outcomes of interest in a geographic area
      • Longitudinal ecological studies: measure trends in disease rates over time in a defined population
    • Experimental designs:
      • Randomized clinical trials or randomized field trials: used to test hypotheses, with investigators controlling the assignment of participants to treatment and control groups

    Observational Designs for Generating Hypotheses

    • Qualitative studies:
      • Investigate clinical issues using anthropologic techniques
      • Identify patterns in data in a structured and sometimes quantitative form
    • Cross-sectional surveys:
      • Quick and easy to perform
      • Useful for determining the prevalence of risk factors and disease frequency
      • Limited by difficulties in determining the temporal relationship between exposure and disease
    • Cross-sectional ecological studies:
      • Relate the frequency of characteristics and outcomes of interest in a geographic area
      • Suggest hypotheses, but cannot draw causal conclusions
    • Longitudinal ecological studies:
      • Measure trends in disease rates over time in a defined population
      • Useful for determining the impact of public health interventions

    Observational Designs for Generating or Testing Hypotheses

    • Cohort studies:
      • Assemble a clearly identified group of people to be studied
      • Assess participants to determine whether they develop diseases of interest
      • Can be prospective (assemble groups in the present and follow up over time) or retrospective (use historical data to define a risk group and follow up to the present)
    • Case-control studies:
      • Select a case group and a control group based on a defined outcome
      • Compare the groups in terms of their frequency of past exposure to possible risk factors
      • Can estimate the relative risk of the outcome (odds ratio), but not the absolute risk

    Randomized Controlled Field Trials (RCFTs)

    • RCFTs are similar to RCCTs, but the intervention is preventive rather than therapeutic and conducted in the community.
    • Participants are randomly allocated to receive the preventive measure (e.g., vaccine, oral drug) or a placebo (e.g., injection of sterile saline, inert pill).
    • Examples of RCFTs include trials of vaccines to prevent paralytic poliomyelitis and aspirin to reduce cardiovascular disease.

    Advantages and Disadvantages of RCFTs and RCCTs

    • Results may take a long time to obtain, unless the effect of the treatment or preventive measure occurs quickly.
    • External validity may be limited, making it unclear which population is represented by the remaining participants in the trial.

    Techniques for Data Summary, Cost-Effectiveness Analysis, and Postapproval Surveillance

    • Meta-analysis is used to summarize information obtained in many single studies on one topic.
    • Decision analysis and cost-effectiveness analysis are used to summarize data and inform clinical or policy decisions.
    • These techniques are used to develop recommendations for clinical preventive services and community preventive services.
    • The U.S. Preventive Services Task Force and the U.S. Community Services Task Force use a hierarchy of evidence, with RCTs at the apex.

    Postapproval Surveillance

    • Longer-term postapproval surveillance (Phase 4 clinical testing) is increasingly important, allowing for a larger study sample and longer observation time.
    • This permits the detection of side effects not seen in earlier studies, as seen in the removal of cyclooxygenase-2 inhibitor medications from the market.

    Research Issues in Epidemiology

    Dangers of Data Dredging

    • Looking for messages in data carries the potential danger of finding those that do not really exist.
    • "Data dredging" can lead to finding associations that do not represent true relationships.
    • Hypothesis development and testing should be based on different data sets.
    • Correlational studies are useful for developing hypotheses, not for testing them.
    • A celebrated example of the problem of data dredging is the reported association between coffee consumption and pancreatic cancer, which was later found to be unfounded.

    The Problem of Multiple Hypotheses

    • With multiple hypotheses, the greater the number of hypotheses tested, the more likely that at least one of them will be found "statistically significant" by chance alone.
    • One possible way to handle this problem is to lower the p-value required before rejecting the null hypothesis.

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    Description

    Research is the process of answering a question that can be answered by appropriately collected data. This quiz explores the different aspects of research design, including descriptive research.

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