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

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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