METHODS IN PSYCHOLOGY
An Overview
Lawrence R. Gordon
Psychology Research Methods I
Something to Start With
 According to 1999 statistics reported on
Vermont Public Radio, women are not as
good at math as men are.
 The evidence presented to support this
conclusion was that the average SAT math
score for women was 40 points lower than
the average score for men.
What do you think about this?
 What is the explanation behind this finding?
Research questions
The effects of __________ on _________ ?
Psychology Research
 Research is the search for the relationships
between variables.
 Two types of variables:


independent variables
dependent variables
 Research tries to find the effects of independent
variables on dependent variables.

“The effects of IV(s) on DV(s) ?”
Independent Variables
 This is the variable of interest because we
are trying to find its effects (how does it
influence other (dependent) variables?)
 Called the predictor variable in some
analyses
 Can be either manipulated or observed
 Examples
Dependent Variables
 We are trying to find out how it is affected
by other (independent) variables
 Called the criterion variable in some
analyses
 Always observed
 Examples
Major Types of Research
 Correlational Research



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independent variable is observed
dependent variable is observed
allows you to see if the IV and the DV are
related
does NOT allow you to make cause-effect
statements about the IV and the DV
Types of Research (cont.)
 Correlational Research (cont.)

Why no cause-effect conclusions?
• Nature of relationship between IV and DV is
unclear!



IV may cause the DV
DV may cause the IV
The third variable problem: Something else
may cause them both
Types of Research (cont.)
 Experimental Research





independent variable is manipulated
dependent variable is observed
all other variables are controlled
allows you to see if the IV causes DV
does allow you to make cause-effect statements
about the IV and the DV
 Example – correlational, then experimental
NPY Disturbances in the
Obese Rat
 Williams et al. (1992)
 Lean and obese rats
 The levels of neuropeptide Y (NPY) were
measured in the rats by radioimmunoassay
 Question

What is the association between NPY and
obesity (do obese rats have higher levels of
NPY?)
NPY Disturbances (cont.)
 Results

Obese rats had higher levels of NPY in the
ARC than did than lean rats
 What can you conclude?



Did increased NPY cause the obesity?
Did obesity cause the increased NPY?
Did something else cause the increased NPY
and the obesity?
NPY Disturbances (cont.)
 Conclusion



Increased levels of NPY are associated with
obesity in rats.
This is correlational research.
No cause-effect conclusions can be drawn.
NPY Disturbances (cont.)


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What was the IV?
How was the IV defined?
What was the DV?
How was the DV defined?
Do you agree with these definitions?
How could the IV and DV be defined
differently, yet still ask the same questions?
Induction of Obesity by NPY
Administration in Normal Rats
 Vettor et al. (1994)
 Lean rats
 2 conditions


one group was infused with NPY for seven
days
one group was infused with vehicle saline
solution for seven days
NPY Administration (cont.)
 Measured food intake and body weight for 14 days
(7 infusion days and the 7 following days)
 Questions



Would the rats with NPY infusions eat more?
Would the rats with NPY infusions weigh more?
If so, would this stop when the infusions stopped?
NPY Administration (cont.)
 Results




Rats with NPY infusions showed dramatic
increases in food intake.
Rats with NPY infusions showed dramatic
increases in body weight.
These increases were reversed when the NPY
infusions stopped.
Graphic presentations >>>>
Food Intake
60
50
40
NPY
Saline
30
20
10
0
1
2
3
4
5
6
7
1
2
3
4
5
6
7
Body Weight Increase
50
40
30
NPY
Saline
20
10
0
1
-10
2
3
4
5
6
7
1
2
3
4
5
6
7
NPY Administration (cont.)
 What can you conclude?



Did NPY cause the increases in food intake and
body weight?
Did the increases in food intake and body
weight cause the NPY infusions?
Did a third variable cause both the increases in
food intake and body weight and the NPY
infusions?
NPY Administration (cont.)
 Conclusion



NPY infusions caused increases in food intake
and in body weight in lean rats.
This is experimental research.
Cause-effect statements can be made.
NPY Administration (cont.)





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What was the IV?
How was the IV defined?
What was the DV?
How was the DV defined?
Do you agree with these definitions?
How could the IV and DV be defined
differently, yet still ask the same questions?
MAJOR RESEARCH METHODS
 Research begins with a question


“The effect(s) of _____ on _____.”
…but there are many ways to try to answer it!
 Research also has implicit or explicit hypotheses:



“If __A__, then __C__.”
A - “antecedent”, C - “consequent”
Falsify: “A, but Not-C” OR “Not-C, but A”
 Willems (1969) classifies research methods:


by degree of manipulation of antecedents
by degree of imposition of units on consequents
Imposition of Units of Response
(Consequent)
Hi
Ex Post Facto Studies
Correlational Studies
True Experiments
(Unobtrusive measures)
Med
Field Studies
(Interviews & Questionnaires)
(Naturalistic Observation)
Lo
Case Studies
Phenomenology
Lo
Med
Manipulation of Antecedent Conditions
Hi
Let’s simplify…
 Major types of research:



Experimental
Correlational
Observational
 We’ll soon start with Experimental and
procede down the list, because advantages
and disadvantages of the other two are best
discussed in reference to it!
OVERVIEW:
The Research Process: 8 Steps
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Develop a research question
Generate a research hypothesis
Form operational definitions
Choose a research design
Evaluate the ethics
Collect data
Analyze data and form conclusions
Report research results