Clinical Research
Methods
Observation
Unsystematic
Controlled
Case Studies
Each has it’s place…but you should be aware of
the limitations of each approach.
Research Methods in Psychology
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By asking questions of a
representative sample,
researchers using the
survey method can
provide useful
information about a much
larger population.
The wording of the
questions can influence
participants' responses.
Research Methods in Psychology
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A case study is an in-depth analysis of a
single person or event.
Although the findings of a case study may
apply only to the person who was studied,
they may provide direction for further
study using other methods.
Research Methods in Psychology
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To study behavior in real-life settings,
psychologists often use naturalistic
observation.
This technique also may suggest research
projects using more controlled
approaches.
In using naturalistic observation, the
onlooker must be unobtrusive and avoid
influencing the behavior being studied.
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Correlational Research
The correlation technique
indicates the degree of
association between 2
variables
Correlations vary in direction:
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Positive association: increases in the
value of variable 1 are associated with
increases in the value of variable 2
Negative association: increases in the
value of variable 1 are associated with
decreases in the value of variable 2
No relation: values of variable 1 are
not related to variable 2 values
Correlations
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Correlations also vary in the strength of
the association
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Zero correlation: no relationship between
the 2 variables
Strong correlation: knowing the value of one
variable permits one to accurately estimate
the value of the other variable
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Strong correlation can be positive or negative
Correlations can be seen in scatter plots
A Zero Correlation
High
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Dependent
variable
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Low
Low
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Independent variable
•
High
A Moderate Positive Correlation
Dependent
variable
High
•
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•
•
•
•
• •
•
•
•
•
•
• • •
• • •
•
Low
Low
Independent variable
High
Correlation Difficulties
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).
True Experimental Design
sample
Assign to
groups
Pre
test
Compare
dependent
variable scores
on posttests
Post
test
Randomize
Pre
test
Control
Condition
Select
Manipulate
experimental
stimulus
Post
test
Internal Validity
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Internal validity in experiments refers to:
whether the independent variable actually
does produce the effect it appears to have
on the dependent variable.
E.G. “Does the Rogerian therapy actually
reduce anxiety symptoms in participants?”
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Does the class-room behavioral mgt program
actually reduce problem behavior?
Threats to Internal Validity
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Selection - the biases which may result in selection of
comparison groups
History - the specific events which occur between the
first and second measurement
Maturation - the processes within subjects which act as
a function of the passage of time
Instrumentation - the changes in the instrument,
observers, or scorers which may produce changes in
outcomes
Statistical regression - the selection of subjects on
the basis of extreme scores or characteristics
Mortality: Experimental attrition -the loss of
subjects
Internal Validity
Internal validity means
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that you have evidence that what you did
in the study (i.e., the program) caused
what you observed (i.e., the outcome) to
happen.
The key issue is Causation
True Experimental Design overcomes all of
the internal validity threats
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Because subjects are randomized to
treatment and control groups, there is no
bias/favorites, both groups are equally likely
to have same qualities
External Validity
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The capacity to generalize findings to
other groups of people and settings.
Threats to external validity
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Selection Bias: Unrepresentative samples
Reactive effects of experimental setting
Multiple treatment interference
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Single Case Experimental
Design
Skinner – Experimental analysis of
behavior
Much more rigorous than Case studies
Establishing a baseline
Two types of single case experimental
designs:
1.
2.
ABAB
Multiple-Baseline designs
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ABAB
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Baseline – Treatment – Baseline –
Treatment
Multiple-Baseline Design
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Home – School - Daycare
Single-Case Design
X
X
X
X
X
Baseline, operant
rate
A
X
X
X
Treatment,
Reinforcement
contingency
B
X
Return to
Baseline, Extinction
A
Multiple Baseline Design
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Useful in testing for a treatment effect
when you believe that the effect is
irreversible.
Baseline data are collected on:
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2 or more behaviors for same individual
Same behavior for 2 or more individuals
Same behavior across 2 or more situations for
the same individual.
Multiple Baseline Design
Behaviors,
People, or
situations
A
B
C
D
Baseline
Baseline
Baseline
Baseline
Behaviors,
People, or
situations
A
B
C
D
Baseline
Baseline
Baseline
Baseline
Treatment
Baseline
Baseline
Baseline
Treatment
Baseline
Baseline
Treatment
Baseline
CBT
Baseline
Baseline
Baseline
CBT
Baseline
Baseline
CBT
Baseline
Dependent variable might be anxiety ratings
Epidemiological Research
Definition: the study of the incidence, prevalence
and distribution of illness/disease in a given
population
Incidence: the number of new cases of a disease
during a given time interval, usually one year. It
can be expressed as a proportion or as a rate.
Prevalence:the total number of cases of the
disease in the population at a given time, or the
total number of cases in the population, divided
by the number of individuals in the population.
Epidemiology
The Greek physician Hippocrates is usually
said to be the "father of epidemiology".
He is the first person known to have examined
the relationships between the occurrence of disease
and environmental influences. He coined the terms
endemic (for diseases usually found in some places
but not in others) and epidemic (for disease that are
seen at some times but not others.
Epidemiology
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Does not definitively establish causal
relationships, but may still lead to
preventative measures to stop the spread
of disease
Dr. John Snow is famous for the suppression
of an 1854 outbreak of cholera in London's Soho
district. He identified the cause of the outbreak as
a public water pump on Broad Street and had the
handle removed, thus ending the outbreak. This has
been perceived as a major event in the history of
public health and can be regarded as the founding event
of the science of epidemiology.