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Chapter 3
The Research Endeavor
Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.
The Scientific Method
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Conducting scientific research involves:
Defining a problem
Specifying a testable hypothesis
Operationalizing the dependent and
independent variables
Chapter 3
Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.
Case Studies
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Detailed histories of individuals who have suffered
some form of psychological disorder.
Case studies have been used for centuries as a way
of trying to understand the experiences of single
individuals and to make more general inferences
about the sources of psychopathology.
Chapter 3
Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.
Correlational Studies
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Continuous
Variable
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Two or more variables are
measured and the correlation
between them is examined
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Group Comparison
Study
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Two or more groups are
compared on the variables of
interest
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Cross-sectional
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Participants assessed at one
point in time
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Longitudinal
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Participants assessed on two or
more occasions over times
Chapter 3
Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.
Chapter 3
Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.
Evaluating Correlational Studies
External validity- the extent to which
the results can be generalized to real life
Disadvantages- cause vs. consequence,
timing, third variable problem
Advantages- reflect real world
problems
Chapter 3
Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.
Epidemiological Studies
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Prevalence rates - the measure of a
condition in a population at a given point in
time
Incidence rates - the number of new
occurrences of a condition (or disease) in a
population over a period of time
Risk factors - traits and lifestyle habits that
increase the risk of disease.
Chapter 3
Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.
Research Methods in Psychology
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Because it can generate cause-and-effect
statements, many psychologists believe that
the experimental method is the most
powerful research approach.
By manipulating an independent variable (the
cause), the researcher determines whether it
influences the dependent variable (the
effect).
Chapter 3
Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.
Research Methods in Psychology
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By manipulating an
independent variable
(the cause), the
researcher determines
whether it influences
the dependent variable
(the effect).
Chapter 3
Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.
Evaluating Human Laboratory Studies
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Advantages
• Researcher has more
control over variables.
• Participants can be
randomly assigned to
groups.
• Appropriate control groups
can be created to rule out
alternative explanations of
important findings.
Chapter 3
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Disadvantages
• Results may not generalize
to outside the laboratory.
• There are ethical limitations.
Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.
Evaluating Therapy Outcome Studies
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Advantages
• They provide help to
people in distress as
research is generated.
Chapter 3
 Disadvantages
• It is difficult to tell which aspect of
therapy led to reduction in the
psychopathology.
• Raises questions about
appropriate control groups.
• Ethical considerations.
• Patients’ needs must be balanced
with the need to administer
standardized therapy.
• Generalizability of results to realworld delivery of therapy is
unclear.
Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.
Multiple Baseline
Chapter 3
Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.
Reversal Designs
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Subjects are observed over a series of
periods in which the IV is and then is not
manipulated
Ex: effect of hostility by parents on social
withdrawal in children
Ex: effects of a drug on schizophrenic
symptoms
Chapter 3
Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.