methods in psychology an overview lawrence r. gordon psychology research methods i
TRANSCRIPT
METHODS IN PSYCHOLOGYAn 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 observedExamples
Dependent Variables
We are trying to find out how it is affected by other (independent) variables
Called the criterion variable in some analyses
Always observedExamples
Major Types of Research
Correlational Research 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 DVExample – correlational, then experimental
NPY Disturbances in the Obese Rat
Williams et al. (1992)Lean and obese ratsThe levels of neuropeptide Y (NPY) were
measured in the rats by radioimmunoassayQuestion
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.)
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 rats2 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
0
10
20
30
40
50
60
1 2 3 4 5 6 7 1 2 3 4 5 6 7
NPYSaline
Body Weight Increase
-10
0
10
20
30
40
50
1 2 3 4 5 6 7 1 2 3 4 5 6 7
NPYSaline
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.)
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
Im
positio
n o
f U
nits
of R
espo
nse
(Co
nse
que
nt)
Hi
Med
Lo
Ex Post Facto Studies True Experiments Correlational Studies
(Unobtrusive measures)
Field Studies
(Interviews & Questionnaires)
(Naturalistic Observation)
Case Studies Phenomenology
Lo Med Hi
Manipulation of Antecedent Conditions
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
Develop a research questionGenerate a research hypothesisForm operational definitionsChoose a research designEvaluate the ethicsCollect dataAnalyze data and form conclusionsReport research results