Overview- Lecture 4
Research Methods
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•
•
•
•
Research Designs: Review of the Basics
Developmental Research Designs
Measurement Effects: Confounds
Better Ways?
Psychometrics
Overview- Lecture 4
Research Methods
•
•
•
•
•
Research Designs: Review of the Basics
Developmental Research Designs
Measurement Effects: Confounds
Better Ways?
Psychometrics
Simple Correlational Designs
Basic Concepts
•Two variables
•Statistic can range from -1 to +1
•Cannot infer cause-effect relationships
Basic Concepts
Simple correlation- Positive
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Reaction
time
Age
Basic Concepts
Simple correlation- Negative
Depression
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Age
Experimental Designs
Design Basics
Independent
•Variable that is manipulated
Variable
•Characteristic
along which people
differ
Dependent
•Variable that is observed
Experimental Designs
Experimental design
•Manipulation of independent variable
•Respondents randomly assigned to groups
•Determine cause and effect
Quasi-experimental design
•Compare groups on predetermined characteristic
•Cannot draw cause and effect conclusions
•Used in most studies of aging
Overview- Lecture 4
Research Methods
•
•
•
•
•
Research Designs: Review of the Basics
Developmental Research Designs
Measurement Effects: Confounds
Better Ways?
Psychometrics
Developmental Research Designs
Basic Designs
Cross-Sectional Design
Longitudinal Design
Cross-sectional Design
Year of test
1970
Year of birth
1980
1990
2000
1920
50 yrs. 60 yrs. 70 yrs. 80 yrs.
1930
40 yrs. 50 yrs. 60 yrs. 70 yrs.
1940
30 yrs. 40 yrs. 50 yrs. 60 yrs.
Longitudinal Design
Year of test
1970
Year of birth
1980
1990
2000
1920
50 yrs. 60 yrs. 70 yrs. 80 yrs.
1930
40 yrs. 50 yrs. 60 yrs. 70 yrs.
1940
30 yrs. 40 yrs. 50 yrs. 60 yrs.
Overview- Lecture 4
Research Methods
•
•
•
•
•
Research Designs: Review of the Basics
Developmental Research Designs
Measurement Effects: Confounds
Better Ways?
Psychometrics
Measurement Effects: Confounds
Effects
Term
Definition
Index of:
Change
within
individual
Age
Chronological age,
measured in years
Cohort
Year or period of birth
Influences
relevant to
history
Time of
measurement
Time of testing
Current
influences
Measurement Effects: Confounds
Basic problem: Cannot separate “age” from “time”
Design
Longitudinal
Cross-Sectional
Confound
Seem to
measure age
“changes”
but..
Age effects cannot
be separated from
historical change
Age effects may be
Measures age
group differences due to cohort
differences
because…
Overview- Lecture 4
Research Methods
•
•
•
•
•
Research Designs: Review of the Basics
Developmental Research Designs
Measurement Effects: Confounds
Better Ways?
Psychometrics
Better Ways?
Sequential Research 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)
Sequential Research Designs:
Schaie’s “Most Efficient Design”
Comparison of Designs
Design
Factor 1
Factor 2
Time sequential
Age
Test Year
Cohort sequential
Age
Cohort
Cross sequential
Cohort
Test year
Alternative Sequential Designs
(Baltes)
Cross-Sectional Sequences
Year of test
1970
Year of birth
1980
1990
2000
1920
50 yrs. 60 yrs. 70 yrs. 80 yrs.
1930
40 yrs. 50 yrs. 60 yrs. 70 yrs.
1940
30 yrs. 40 yrs. 50 yrs. 60 yrs.
Alternative Sequential Designs
(Baltes)
Longitudinal Sequences
Year of test
1970
Year of birth
1980
1990
2000
1920
50 yrs. 60 yrs. 70 yrs. 80 yrs.
1930
40 yrs. 50 yrs. 60 yrs. 70 yrs.
1940
30 yrs. 40 yrs. 50 yrs. 60 yrs.
Correlational Approaches:
Multivariate Correlational
Designs
• Multiple variables
• Causal relationships estimated
Correlational Approaches in Research on Aging:
Multivariate Correlational Designs
Types
Multiple regression analysis
•Predictor variables used to estimate dependent variable
•Can suggest and test causal relationships
Structural equations
•Diagram a set of relationships
•Test data against hypothesized model
Correlational Approaches in Research on Aging:
Multivariate Correlational Designs
See text page 68
Overview- Lecture 4
Research Methods
•
•
•
•
•
Research Designs: Review of the Basics
Developmental Research Designs
Measurement Effects: Confounds
Better Ways?
Psychometrics
Measurement Issues: Psychometrics
Psychometrics
Forms of reliability Test-retest
Test gives consistent
responses
Give test on two occasions
Internal consistency
Test items yield similar answers
Content
Forms of validity Factual content
Test measures what it measured correctly
is supposed to
Construct
measure
Scores fit with theory
Criterion
Scores predict actual performance
Need to be established on all age groups tested