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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
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... .
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..
...
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Basic ConceptsBasic Concepts
AgeAge
DepressionDepression
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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