Chapter 07 ppt

Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Chapter 7: Gathering Evidence
for Practice

Chapter Highlights
• Epidemiologic research defined
• Descriptive versus analytical research
• Strengths and limitations of epidemiologic research
methodology
• Applying epidemiologic research to practice

Question
Is the following statement True or False?
In descriptive studies, the researcher relies on
comparisons between groups to determine the role of
various risk factors in causing the problem.

Answer
False
Rationale: In analytical studies, the researcher relies
on comparisons between groups to determine the role
of various risk factors in causing the problem. In
descriptive studies, the researcher collects information
to characterize and summarize the health event or
problem.

Epidemiologic Research
• Identify community/public health problems
• Describe natural history and etiology of diseases

Observational Studies
• In descriptive studies, the researcher collects information
to characterize and summarize the health event or
problem.
• In analytical studies, the researcher relies on
comparisons between groups to determine the role of
various risk factors in causing the problem.

Question
Cohort studies involve an in-depth analysis of an
individual, group, or social institution.

Answer
False
Rationale: Case studies involve an in-depth analysis of an
individual, group, or social institution. Cohort studies,
sometimes referred to as prospective studies, are
longitudinal studies, which monitor subjects over time to
find associations between risk factors and health
outcomes.

Types of Descriptive Studies
• Case studies involve an in-depth analysis of an
individual, group, or social institution
• Cross sectional studies are those in which a sample of
persons from a population is enrolled and their exposures
and health outcomes are measured simultaneously.

Question
Case–control studies, also known as prospective studies,
work backward from the effect to the suspected cause.

Answer
False
Rationale: Case–control studies, also known as
retrospective studies, work backward from the effect to
the suspected cause. Cohort studies, sometimes referred
to as prospective studies, are longitudinal studies,
monitor subjects over time to find associations between
risk factors and health outcomes.

Types of Analytical Studies
• Cohort studies, sometimes referred to as prospective
studies, are longitudinal studies, which monitor subjects
over time to find associations between risk factors and
health outcomes.
RR = Incidence rate of people exposed
Incidence rate of people not exposed
Causality—relationship between two variables in which
the presence or absence of one variable (the
“cause”) determines the presence or absence of the
other (the “effect”)

Types of Analytical Studies (cont.)
• Case–control studies, also known as retrospective
studies, work backward from the effect to the suspected
cause.
• Subjects are selected on the basis of the presence or
absence of the disease or outcome in question—one
group of people (case-subjects) with the health problem
and another group without the health problem (controls)
• The relationship between exposure and outcome in a
case-control study is quantified by calculating the odds
ratio (OR). The OR is an estimate of RR that is
interpreted in the same manner as RR.

Advantages of Case–Control Studies
• Allow for the examination of multiple exposures for a
single outcome
• Are suitable for studying rare diseases and those with
long latency periods
• Require fewer case-subjects
• Are generally quicker and less expensive to conduct than
cohort studies, making them well suited for an outbreak
investigation

Disadvantages of Case–Control Studies
• They are not appropriate for studying rare exposures.
• They are subject to bias because of the method used to
select controls.
• They do not allow the direct measure of the incidence of
disease.

Question
Intervention study is the epidemiologic investigation
designed to test a hypothesized relationship by modifying
an identified factor in a population. The study is
preventive.

Answer
False
Rationale:Intervention study is the epidemiologic
investigation designed to test a hypothesized relationship
by modifying an identified factor in a population. Studies
may be therapeutic (clinical) or preventive.

Intervention (Experimental) Studies
• Intervention study—epidemiologic investigation designed
to test a hypothesized relationship by modifying an
identified factor in a population.
– Preventive trial—study where the investigator
provides a specific preventive measure to the group
under study and follows the group to determine the
effects of the intervention
– Therapeutic trial—clinical trial where the investigator
provides a specific treatment (therapy) to the group
under study and follows the group to determine the
effects of the treatment

Statistics
• P value, generally at .05, to ensure that the study
results are not due to chance alone and to avoid
committing a type I error.
• A type I error occurs when the null hypothesis (H0, a
theory that has been put forward, either because it is
believed to be true or because it is to be used as a basis
for argument) is rejected when it is true.
• A type II error occurs when one rejects the alternative
hypothesis (Ha) (fails to reject the null hypothesis) when
the alternative hypothesis is true.

Question
The “gold standard” for research design is the
randomized, experimental group design.

Answer
False
Rationale: The “gold standard” for research design is the
randomized, control group design.

Community Health Nurses
• Consumers of health-related research, which is used to
inform and educate the public
• Having a basic understanding of research methods allows
nurses to interpret and critically analyze studies
described in newspapers, magazines, and scientific
journals, as well as on the Internet
• Allows nurses to generate research questions related to
problems identified in their practice

Chapter 07 ppt

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