Overview- Lecture 4Research Methods

• Research Designs: Review of the Basics

• Developmental Research Designs

• Measurement Effects: Confounds

• Better Ways?

• Psychometrics

Overview- Lecture 4Research Methods

• Research Designs: Review of the Basics

• Developmental Research Designs

• Measurement Effects: Confounds

• Better Ways?

• Psychometrics

Simple Correlational DesignsSimple Correlational Designs

•Two variablesTwo variables•Statistic can range from -1 to +1Statistic can range from -1 to +1•Cannot infer cause-effect relationshipsCannot infer cause-effect relationships

Basic ConceptsBasic Concepts

Simple correlationSimple correlation- - PositivePositive Simple correlationSimple correlation- - PositivePositive

AgeAge

ReactionReactiontimetime

..

.

... .

.

..

.

..

...

....

.

.

Basic ConceptsBasic Concepts

AgeAge

DepressionDepression

..

.

....

.

..

...

.. .... ..

.

Simple correlationSimple correlation- - NegativeNegative Simple correlationSimple correlation- - NegativeNegative

Basic ConceptsBasic Concepts

VariableVariable

IndependentIndependent

Experimental DesignsExperimental Designs

DependentDependent

Design BasicsDesign Basics

•Variable that is manipulatedVariable that is manipulated

•Variable that is observedVariable that is observed

•Characteristic Characteristic along which people along which people differdiffer

•Manipulation of independent variableManipulation of independent variable•Respondents randomly assigned to groupsRespondents randomly assigned to groups•Determine cause and effectDetermine cause and effect

•Compare groups on predetermined characteristicCompare groups on predetermined characteristic•Cannot draw cause and effect conclusionsCannot draw cause and effect conclusions•Used in most studies of agingUsed in most studies of aging

Experimental DesignsExperimental Designs

Experimental designExperimental designExperimental designExperimental design

Quasi-experimental designQuasi-experimental designQuasi-experimental designQuasi-experimental design

Overview- Lecture 4Research Methods

• Research Designs: Review of the Basics

• Developmental Research Designs

• Measurement Effects: Confounds

• Better Ways?

• Psychometrics

Developmental Research DesignsDevelopmental Research Designs

Cross-Sectional DesignCross-Sectional DesignCross-Sectional DesignCross-Sectional Design

Longitudinal DesignLongitudinal DesignLongitudinal DesignLongitudinal Design

Basic DesignsBasic Designs

19201920

19301930

19401940

19701970 19801980 19901990 20002000

50 yrs. 60 yrs. 70 yrs. 80 yrs.

40 yrs.

40 yrs.

60 yrs.

60 yrs.

50 yrs.

50 yrs.

70 yrs.

30 yrs.

Year of testYear of test

Year of birthYear of birth

Cross-sectional DesignCross-sectional Design

19201920

19301930

19401940

19701970 19801980 19901990 20002000

50 yrs. 60 yrs. 70 yrs. 80 yrs.

40 yrs.

40 yrs.

60 yrs.

60 yrs.

50 yrs.

50 yrs.

70 yrs.

30 yrs.

Year of testYear of test

Year of birthYear of birth

Longitudinal DesignLongitudinal Design

Overview- Lecture 4Research Methods

• Research Designs: Review of the Basics

• Developmental Research Designs

• Measurement Effects: Confounds

• Better Ways?

• Psychometrics

Measurement Effects: ConfoundsMeasurement Effects: Confounds

AgeAge

CohortCohort

Time of Time of measurementmeasurement

EffectsEffects

Chronological age, Chronological age, measured in yearsmeasured in years

Year or period of birthYear or period of birth

Time of testingTime of testing

TermTerm DefinitionDefinition Index of:Index of:

Change Change within within individualindividual

Influences Influences relevant to relevant to historyhistory

Current Current influencesinfluences

LongitudinalLongitudinalSeem to measure age “changes” but..

ConfoundConfoundDesignDesign

Cross-SectionalCross-Sectional

Basic problem: Cannot separate “age” from “time”Basic problem: Cannot separate “age” from “time”

Measurement Effects: ConfoundsMeasurement Effects: Confounds

Age effects cannot be separated from historical change

Measures age group differences because…

Age effects may be due to cohort differences

Overview- Lecture 4Research Methods

• Research Designs: Review of the Basics

• Developmental Research Designs

• Measurement Effects: Confounds

• Better Ways?

• Psychometrics

Better Ways?Better Ways?Sequential Research Designs Sequential Research Designs

(Shaie’s Designs)(Shaie’s Designs)

• Involve a “sequence” of designs

• Allow inferences to be made about age effects and historical influences (cohort effects and time of measurement/test year effects)

Time sequentialTime sequential Age

Factor 2Factor 2

Cohort sequentialCohort sequential

DesignDesign Factor 1Factor 1

Test Year

Cross sequentialCross sequential

CohortAge

Cohort Test year

Sequential Research Designs:Sequential Research Designs:Schaie’s “Most Efficient Design”Schaie’s “Most Efficient Design”

Comparison of DesignsComparison of Designs

1920

1930

1940

1970 1980 1990 2000

50 yrs.50 yrs. 60 yrs. 70 yrs. 80 yrs.

40 yrs.40 yrs.

40 yrs.40 yrs.

60 yrs.

60 yrs.

50 yrs.50 yrs.

50 yrs.

70 yrs.

30 yrs.

Cross-Sectional SequencesCross-Sectional Sequences

Alternative Sequential Designs Alternative Sequential Designs (Baltes)(Baltes)

Year of testYear of test

Year of birthYear of birth

1920

1930

1940

1970 1980 1990 2000

50 yrs.50 yrs. 60 yrs.60 yrs. 70 yrs.70 yrs. 80 yrs.

40 yrs.

40 yrs.

60 yrs.60 yrs.

60 yrs.

50 yrs.50 yrs.

50 yrs.

70 yrs.70 yrs.

30 yrs.

Longitudinal SequencesLongitudinal Sequences

Alternative Sequential Designs Alternative Sequential Designs (Baltes)(Baltes)

Year of testYear of test

Year of birthYear of birth

Correlational Approaches:Correlational Approaches:Multivariate Correlational Multivariate Correlational

DesignsDesigns

• Multiple variables

• Causal relationships estimated

TypesTypes

•Predictor variables used to estimate dependent variablePredictor variables used to estimate dependent variable•Can suggest and test causal relationshipsCan suggest and test causal relationships

Multiple regression analysisMultiple regression analysisMultiple regression analysisMultiple regression analysis

•Diagram a set of relationshipsDiagram a set of relationships•Test data against hypothesized modelTest data against hypothesized model

Structural equationsStructural equationsStructural equationsStructural equations

Correlational Approaches in Research on Aging:Correlational Approaches in Research on Aging:

Multivariate Correlational DesignsMultivariate Correlational Designs

Correlational Approaches in Research on Aging:Correlational Approaches in Research on Aging:

Multivariate Correlational DesignsMultivariate Correlational Designs

See text page 68See text page 68See text page 68See text page 68

Overview- Lecture 4Research Methods

• Research Designs: Review of the Basics

• Developmental Research Designs

• Measurement Effects: Confounds

• Better Ways?

• Psychometrics

Measurement Issues: PsychometricsMeasurement Issues: Psychometrics

Forms of reliabilityForms of reliability

Forms of validityForms of validity

Test-retestTest-retest

Internal consistencyInternal consistency

ContentContent

ConstructConstruct

CriterionCriterion

Give test on two occasions

Test items yield similar answers

Test measures what it is supposed to measure

Test gives consistent responses

Factual content measured correctly

Scores fit with theory

Scores predict actual performance

Need to be established on all age groups testedNeed to be established on all age groups testedNeed to be established on all age groups testedNeed to be established on all age groups tested

PsychometricsPsychometrics