Research MethodsResearch Methods

1.1. Case studiesCase studies

2.2. Correlational researchCorrelational research

3.3. Experimental researchExperimental research

**will need to know more detail than is in your **will need to know more detail than is in your book about these topicsbook about these topics

Case StudyCase Study

Murray (1938)Murray (1938)

personology = need to understand the whole personology = need to understand the whole person as a coherent entity (vs. just parts of person as a coherent entity (vs. just parts of people)people)

in-depth study of one personin-depth study of one person

Case StudyCase Study

Useful in several instances:Useful in several instances:1.1. Rare or unusual situations Rare or unusual situations

Piano virtuosoPiano virtuoso Mass murderersMass murderers

2.2. To demonstrate possibilitiesTo demonstrate possibilities HypnosisHypnosis

3.3. To demonstrate a treatmentTo demonstrate a treatment PTSD treatment in childPTSD treatment in child

4.4. As disconfirming evidenceAs disconfirming evidence Shatter assumptions about abilitiesShatter assumptions about abilities

Case StudyCase Study

StrengthsStrengths Depth and detailDepth and detail Capture complexityCapture complexity

WeaknessesWeaknesses Problem of generalization: idiosyncratic subjectProblem of generalization: idiosyncratic subject Problem of generalization: experimenter biases and Problem of generalization: experimenter biases and

subjective impressionssubjective impressions Entangled relationships among variablesEntangled relationships among variables

Correlational DesignCorrelational Design

= a study that assesses the extent to which two = a study that assesses the extent to which two variables are relatedvariables are related

Defines the relationship in Defines the relationship in quantitativequantitative terms terms Correlational (“co-related”)Correlational (“co-related”)

When one variable changes in value, what When one variable changes in value, what happens to the other variable?happens to the other variable?

Correlation ExampleCorrelation Example

Is there a relationship between self-esteem and GPA?Is there a relationship between self-esteem and GPA?

1.1. Need to have different levels of my first variable: Need to have different levels of my first variable: self-esteemself-esteem

Very high self-esteem -------- ?Very high self-esteem -------- ?Moderately high self-esteem--?Moderately high self-esteem--?Average self-esteem -----------?Average self-esteem -----------?Moderately low self-esteem --?Moderately low self-esteem --?Very low self-esteem ----------?Very low self-esteem ----------?

Correlation ExampleCorrelation Example

Raw Data:Raw Data:

Self-esteem scoreSelf-esteem score GPAGPA

TimTim 4242 3.83.8

BartBart 1010 1.41.4

KelseyKelsey 1515 2.52.5

KimKim 2222 3.13.1

Etc.Etc.

Correlation ExampleCorrelation Example

See scatterplot of dataSee scatterplot of data

Self-esteem and GPA data

0

0.5

1

1.5

2

2.5

3

3.5

4

0 5 10 15 20 25 30 35 40 45

self-esteem

GPA Series1

Direction of CorrelationDirection of Correlation Scatterplot showed a Scatterplot showed a positivepositive correlation correlation

As one variable increased, the second variable also increasedAs one variable increased, the second variable also increased As self-esteem goes up, academic achievement also goes upAs self-esteem goes up, academic achievement also goes up Think of some examples of positively correlated variablesThink of some examples of positively correlated variables

NegativeNegative (inverse) correlation (inverse) correlation As on variable increases, the second variable decreases (i.e. one gets As on variable increases, the second variable decreases (i.e. one gets

bigger, the other gets smaller)bigger, the other gets smaller) As amount of alcohol intake increases, motor control decreasesAs amount of alcohol intake increases, motor control decreases Think of examples of negatively correlated variablesThink of examples of negatively correlated variables

= = direction of the correlationdirection of the correlation

Strength of CorrelationStrength of Correlation

How strongly related are the two variables of How strongly related are the two variables of interest?interest? the “sloppiness” of associationthe “sloppiness” of association Degree of accuracy with which you can make a Degree of accuracy with which you can make a

prediction about 2prediction about 2ndnd variable given value of the variable given value of the first variablefirst variable

Ranges from -1 to 1Ranges from -1 to 1 -1 and 1 are very strong (perfect) correlations-1 and 1 are very strong (perfect) correlations 0 is no correlation; no relationship0 is no correlation; no relationship

Correlation – strength and directionCorrelation – strength and direction

Correlation ExampleCorrelation Example High Self-esteem and GPAHigh Self-esteem and GPA

Does (A) lead to (B)? Or is the other way around? Or, are Does (A) lead to (B)? Or is the other way around? Or, are there other factors that lead to both (A) and (B)? there other factors that lead to both (A) and (B)?

Two independent carefully conducted studies found that there Two independent carefully conducted studies found that there is no causal relationship between these two factors. They are is no causal relationship between these two factors. They are correlated because both of them are correlated to some other correlated because both of them are correlated to some other factors: intelligence and family social status. factors: intelligence and family social status.

**Correlations do NOT tell us that one variable CAUSES the **Correlations do NOT tell us that one variable CAUSES the other variable.other variable.

A recent Morgan-Gallup Poll in the US of A recent Morgan-Gallup Poll in the US of 1009 people asked:1009 people asked:

““Does correlation imply causation?”Does correlation imply causation?”

64% YES64% YES

38% NO38% NO

8% undecided8% undecided

Correlational researchCorrelational research

StrengthsStrengths Can study a broad range of variablesCan study a broad range of variables Can look at multiple variables at one timeCan look at multiple variables at one time Large samples are easily obtainedLarge samples are easily obtained

WeaknessesWeaknesses Relationships established are associational, not causalRelationships established are associational, not causal Individuals not studies in-depthIndividuals not studies in-depth Potential problems with reliability and validity of self-Potential problems with reliability and validity of self-

report measuresreport measures

Experimental DesignExperimental Design

Allows us to determine cause and effectAllows us to determine cause and effect

Defining characteristics:Defining characteristics:

1.1. Manipulation of variablesManipulation of variables Independent variableIndependent variable Dependent variableDependent variable

2.2. Experimental control of other variablesExperimental control of other variables

3.3. Random assignment to groupsRandom assignment to groups

ExampleExample

Learned helplessnessLearned helplessness All subjects first hear a very loud noiseAll subjects first hear a very loud noise 3 groups:3 groups:

Can end the noise by pushing a buttonCan end the noise by pushing a button Cannot stop the noiseCannot stop the noise Control group – doesn’t hear noiseControl group – doesn’t hear noise

Put in 2Put in 2ndnd situation where they could end a loud noise by situation where they could end a loud noise by moving their hand. D.V. was response latency (how soon moving their hand. D.V. was response latency (how soon did they move hand?)did they move hand?)

11stst and 3 and 3rdrd groups learned quickly to move hand; 2 groups learned quickly to move hand; 2ndnd group group sat passively and did nothingsat passively and did nothing

Experimental DesignExperimental Design StrengthsStrengths

Can tease out cause and effectCan tease out cause and effect Allows for strict control of variablesAllows for strict control of variables

WeaknessesWeaknesses Many questions may not be able to be answered using this Many questions may not be able to be answered using this

method – i.v. cannot be varied (e.g. sex, age, birth order, method – i.v. cannot be varied (e.g. sex, age, birth order, effects of child abuse)effects of child abuse)

May be artificial and limitedMay be artificial and limited Causal effects may not hold when the complexity of actual Causal effects may not hold when the complexity of actual

human behavior is consideredhuman behavior is considered Involves brief exposures and may miss important processes Involves brief exposures and may miss important processes

that occur over timethat occur over time

Example from the news/class activityExample from the news/class activity

EXAMPLE 1EXAMPLE 1:: "MARRIAGE SLOWS CANCER DEATHS""MARRIAGE SLOWS CANCER DEATHS" Evidence that married people have a better Evidence that married people have a better

chance of surviving cancer than do singles chance of surviving cancer than do singles means that the unmarried might be good means that the unmarried might be good targets for cancer-prevention programs. targets for cancer-prevention programs. Married people with cancer had a 23% higher Married people with cancer had a 23% higher overall survival rate than the unmarried.overall survival rate than the unmarried.

Another exampleAnother example

Example 2:Example 2: Children who are aggressive tend to watch a Children who are aggressive tend to watch a

higher proportion of violent television than higher proportion of violent television than children who are not highly violent or children who are not highly violent or aggressive aggressive

What type of design?What type of design? What can we conclude?What can we conclude?

CategorizeCategorize

I give students a questionnaire that measures I give students a questionnaire that measures how much they like sensation seeking how much they like sensation seeking activities. I then ask them about current drug activities. I then ask them about current drug use. I find that students who are high in use. I find that students who are high in sensation seeking engage in more drug use sensation seeking engage in more drug use than students low in sensation seeking. than students low in sensation seeking.

What type of study? What type of study? What type of relationship?What type of relationship?

CategorizeCategorize

I randomly assign children with behavior problems to I randomly assign children with behavior problems to two types of play groups: one group is structured and two types of play groups: one group is structured and organized and the other group has no rules. I organized and the other group has no rules. I measure the number of aggressive behaviors in each measure the number of aggressive behaviors in each group. group.

What type of research is this?What type of research is this? What are the independent and dependent variables?What are the independent and dependent variables? Does the type of research change if I look at children Does the type of research change if I look at children

with behavior problems and compare them to with behavior problems and compare them to children without behavior problems?children without behavior problems?

CategorizeCategorize

Over the course of several years, I interview Over the course of several years, I interview three adolescents who live in poverty. I am three adolescents who live in poverty. I am interested in the impact that poverty has on interested in the impact that poverty has on their lives. their lives.

What type of study?What type of study?