Correlational Research Inferential/Descriptive Statistic (r) Describes strength of linear relation between two variables Strength of relation = degree

Correlational ResearchCorrelational ResearchInferential/Descriptive Statistic (r) Describes strength of linear relation between two

variablesStrength of relation = degree of associationDoes knowing an individual’s score on A tell you much about that individual’s score on B? How much does it tell you?

Some properties of r

Ranges between -1 and 1 inclusive

Sign (+ or -) gives direction of relation

Absolute value gives strength

r2 gives proportion of variance accounted for

CorrelationsCorrelations

Performance IQ

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l IQ

140

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100

90

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60

Correlation between VIQ and PIQ = +.53

Characterized as strong and positive


Correlation between C and Behavioral Impulsivity = -.41

Characterized as moderate-strong and negative

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Correlation between C and Family SES = -.15

Characterized as weak-negligible

family social class

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Correlational ResearchCorrelational Research

Disadvantages:1) correlation does not indicate causation2) problems with self-report method

Advantages:1) can collect much information from many subjects at one time2) can study a wide range of variables and their interrelations3) study variables that are not easily produced in the laboratory

Correlational ResearchCorrelational ResearchDefinition:

Seeks to establish a relation/association/correlation between two or more variables that do not readily lend themselves to experimental manipulation

Disadvantages:1) correlation does not indicate causation (6slide

causation example)2) problems with self-report method Advantages:1) can collect much information from many subjects at one time2) can study a wide range of variables and their interrelations3) study variables that are not easily produced in the laboratory

Microsoft PowerPoint Presentation

Correlation is not CausationCorrelation is not CausationThree ways in which A and B may be causally related

A B

A causes B (either directly or indirectly)

B causes A (either directly or indirectly)

B A

A third variable causes both A and B

C

A

B

Correlations Inform Correlations Inform CausationCausation

Causation implies Correlation

Design or theory informs direction of influence

Specify and measure likely third variablesControl for third variables in model

If association between A and B remains, then third variable explanation does not hold

If A and B are causally related, they must be correlated

Can model third variable effects

Longitudinal design

Experimental design

Appeal to strong theory

Case In PointCase In Point Lynam, D.R., Moffitt, T.E., & Stouthamer-Loeber, M.A. (1993).

Explaining the relation between IQ and delinquency: Class, race, test motivation, school achievement, or self-control? Journal of Abnormal Psychology, 102, 187-196. IQ is negatively correlated with delinquency

Think of some ways this relationship could work. In other words, why or how might lower IQ be related to delinquency?

What are other possibilities?

Delinquency leads to low Delinquency leads to low IQ?IQ?

Third Variables?Third Variables?

What are the likely candidates?

Social Class

Impulsivity

Race

What happens when they are included?

Partial r = -.15

Original r = -.25

Significant relation remains

IQ IQ Delinquency via School Delinquency via School Achievement?Achievement?

What happens when school achievement is included?

Correlational ResearchCorrelational ResearchDefinition:

Seeks to establish a relation/association/correlation between two or more variables that do not readily lend themselves to experimental manipulation

Disadvantages:1) correlation does not indicate causation2) problems with self-report method

Advantages:1) can collect much information from many subjects at one time2) can study a wide range of variables and their interrelations3) study variables that are not easily produced in the laboratory



Correlational Research Correlational Research ExampleExample

Reformulated learned helplessness:

When people find they are helpless, they ask whythree dimensions of causal attributions

internal-externalspecific-globalstable-unstable

internal, global, and stable attributions lead to depression

Attributional Style QuestionnaireMicrosoft PowerPoint Presentation

Should find correlation between I, S, G attributional style and level of depression

Attributional Style Attributional Style QuestionnaireQuestionnaire

You have been looking unsuccessfully for a job for some time.1. Write down one major cause.

2. Is the cause of your unsuccessful job search due to something about you, or to, something about other people or circumstances ?Totally due Totally due to others 1 2 3 4 5 6 7 to me

3. In the future, when looking for a job, will this cause again be present? Will never again Will alwaysbe present1 2 3 4 5 6 7be present

4. Is this cause something that influences just looking for a job, or does it also influence other areas of your life? Influences this Influences allsituation 1 2 3 4 5 6 7situations

5. How important would this situation be if it happened to you? Not at all Extremelyimportant1 2 3 4 5 6 7important

Quasi-Experimental Quasi-Experimental ResearchResearch

Definition: Blends correlational and experimental approaches. Typically examines interaction between an individual difference variable and an experimental manipulation(expericorr example)

Disadvantages: similar to those of correlational research

1 Third variable problem still remainsAdvantages: similar to those of correlational research

1 Can tease out cause and effect somewhat better if have manipulated variable


Quasi-experimental Quasi-experimental ExampleExample

Discounting: Tendency to choose smaller, immediately available rewards over larger, delayed rewards

Hypothetical Money Choice TaskChoice is offered: smaller, immediately available reward or larger delayed oneChooses immediate reward, task is over and

value is recorded

Chooses delayed reward, new choice with larger immediate reward is offered

Waiting for larger immediate reward before switching shows less discounting

HMCT (Version 1)HMCT (Version 1)

or

$5 now

You can have:

$100 in 1 week

Which would you choose?

$5 now

$100 in 1 week


or

$10 now

You can have:

$100 in 1 week


$10 now

$100 in 1 week


or

$15 now

You can have:

$100 in 1 week


$15 now

$100 in 1 week

and so on….


or

$5 now

You can have:

$100 in 1 month


$5 now

$100 in 1 month


or

$10 now

You can have:

$100 in 1 month


$10 now

$100 in 1 month

Hypothetical ResultsHypothetical Results

Effect of Condition:

Version 1

$80.25

Version 2

$65.25

$65.00

Interaction of Condition and SS: Version 1

$85.25

$65.00

Version 2

$70.25

Low SS

High SS


Definition: Blends correlational and experimental approaches. Typically examines interaction between an individual difference variable and an experimental manipulation

Disadvantages: similar to those of correlational research

1 Third variable problem still remainsAdvantages: similar to those of correlational research

1 Can tease out cause and effect somewhat better if have manipulated variable

Locus of Control ScaleLocus of Control ScaleFor each pair of statements, choose the one with which you most agree:

1a. Many of the unhappy things in people's lives are due partly to bad luck.1b. People's misfortunes result from the mistakes they make.

2a. One of the major reasons we have wars is that people don't take enough interest in politics.2b. There will always be wars, no matter how hard people try to prevent them.

3a. Sometimes I can't understand how teachers arrive at the grades they give.3b. There is a direct connection between how hard I study and the grades I get.

4a. The average citizen can have an influence in government decisions.4b. This world is run by the few people in power and there isn't much the little guy can do about it.

Scoring: Give yourself one point for each of the following: 1a, 2b, 3a, 4b


Locus of ControlBeliefs about one’s ability to influence outcomesSimilar to learned helplessnessAssessed with LOC scale

Selected participants to be high or low in external LOCRandomly assigned participants to one of two conditions

Performance task with shock that is very easy to learn to avoidPerformance task with shock that is hard to learn to avoid

Findings in line with hypothesesIn easy task most people learned how to avoid shockIn harder task, Ps with high external LOC were less likely to learn


Problems to Look ForProblems to Look ForExperimental confound: when another variable is allowed to vary with the independent variable.

Third variable problem

Nonrandom samples: when samples are selected so that not everyone has an equal opportunity to participate.Failure to replicate: single experiments do not constitute facts.

Failure to include relevant comparison groups: lack an adequate baseline or normative data.

(Example)

Failure to Include Failure to Include ComparisonComparison

Make people happy or sad and examine effects on aggression:

Sad Happy

Aggression 7.5 3.0

The meaning depends on a control group:

Sad Control Happy

1) 7.5 7.5 3.0

2) 7.5 5.0 3.0

3) 7.5 3.0 3.0

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Correlational Research Inferential/Descriptive Statistic (r) Describes strength of linear relation between two variables Strength of relation = degree