Research Methods
1.
2.
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Case studies
Correlational research
Experimental research
**will need to know more detail than is in your
book about these topics
Case Study
Murray (1938)
personology = need to understand the whole
person as a coherent entity (vs. just parts of
people)
in-depth study of one person
Case Study
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Useful in several instances:
1.
Rare or unusual situations
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2.
To demonstrate possibilities
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Hypnosis
To demonstrate a treatment
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4.
Piano virtuoso
Mass murderers
PTSD treatment in child
As disconfirming evidence
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Shatter assumptions about abilities
Case Study
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Strengths
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Depth and detail
Capture complexity
Weaknesses
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Problem of generalization: idiosyncratic subject
Problem of generalization: experimenter biases and
subjective impressions
Entangled relationships among variables
Correlational Design
= a study that assesses the extent to which two
variables are related
 Defines the relationship in quantitative terms
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Correlational (“co-related”)
When one variable changes in value, what
happens to the other variable?
Correlation Example
Is there a relationship between self-esteem and GPA?
1.
Need to have different levels of my first variable:
self-esteem
Very high self-esteem -------- ?
Moderately high self-esteem--?
Average self-esteem -----------?
Moderately low self-esteem --?
Very low self-esteem ----------?
Correlation Example
Raw Data:
Self-esteem score
Tim
42
Bart
10
Kelsey 15
Kim
22
Etc.
GPA
3.8
1.4
2.5
3.1
Correlation Example
See scatterplot of data
Self-esteem and GPA data
4
3.5
3
GPA
2.5
2
Series1
1.5
1
0.5
0
0
5
10
15
20
25
self-esteem
30
35
40
45
Direction of Correlation
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Scatterplot showed a positive correlation
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As one variable increased, the second variable also increased
As self-esteem goes up, academic achievement also goes up
Think of some examples of positively correlated variables
Negative (inverse) correlation
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As on variable increases, the second variable decreases (i.e. one gets
bigger, the other gets smaller)
As amount of alcohol intake increases, motor control decreases
Think of examples of negatively correlated variables
= direction of the correlation
Strength of Correlation
How strongly related are the two variables of
interest?
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the “sloppiness” of association
Degree of accuracy with which you can make a
prediction about 2nd variable given value of the
first variable
Ranges from -1 to 1
-1 and 1 are very strong (perfect) correlations
0 is no correlation; no relationship
Correlation – strength and direction
Correlation Example
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High Self-esteem and GPA
Does (A) lead to (B)? Or is the other way around? Or, are
there other factors that lead to both (A) and (B)?
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Two independent carefully conducted studies found that there
is no causal relationship between these two factors. They are
correlated because both of them are correlated to some other
factors: intelligence and family social status.
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**Correlations do NOT tell us that one variable CAUSES the
other variable.
A recent Morgan-Gallup Poll in the US of
1009 people asked:
“Does correlation imply causation?”
64% YES
38% NO
8% undecided
Correlational research
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Strengths
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Can study a broad range of variables
Can look at multiple variables at one time
Large samples are easily obtained
Weaknesses
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Relationships established are associational, not causal
Individuals not studies in-depth
Potential problems with reliability and validity of selfreport measures
Experimental Design
Allows us to determine cause and effect
Defining characteristics:
1.
Manipulation of variables
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3.
Independent variable
Dependent variable
Experimental control of other variables
Random assignment to groups
Example
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Learned helplessness
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All subjects first hear a very loud noise
3 groups:
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Can end the noise by pushing a button
Cannot stop the noise
Control group – doesn’t hear noise
Put in 2nd situation where they could end a loud noise by
moving their hand. D.V. was response latency (how soon
did they move hand?)
1st and 3rd groups learned quickly to move hand; 2nd group
sat passively and did nothing
Experimental Design
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Strengths
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Can tease out cause and effect
Allows for strict control of variables
Weaknesses
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Many questions may not be able to be answered using this
method – i.v. cannot be varied (e.g. sex, age, birth order,
effects of child abuse)
May be artificial and limited
Causal effects may not hold when the complexity of actual
human behavior is considered
Involves brief exposures and may miss important processes
that occur over time
Example from the news/class activity
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EXAMPLE 1:
"MARRIAGE SLOWS CANCER DEATHS"
Evidence that married people have a better
chance of surviving cancer than do singles
means that the unmarried might be good
targets for cancer-prevention programs.
Married people with cancer had a 23% higher
overall survival rate than the unmarried.
Another example
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Example 2:
Children who are aggressive tend to watch a
higher proportion of violent television than
children who are not highly violent or
aggressive
What type of design?
What can we conclude?
Categorize
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I give students a questionnaire that measures
how much they like sensation seeking
activities. I then ask them about current drug
use. I find that students who are high in
sensation seeking engage in more drug use
than students low in sensation seeking.
What type of study?
What type of relationship?
Categorize
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I randomly assign children with behavior problems to
two types of play groups: one group is structured and
organized and the other group has no rules. I measure
the number of aggressive behaviors in each group.
What type of research is this?
What are the independent and dependent variables?
Does the type of research change if I look at children
with behavior problems and compare them to
children without behavior problems?
Categorize
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Over the course of several years, I interview
three adolescents who live in poverty. I am
interested in the impact that poverty has on
their lives.
What type of study?