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quasi experimental design
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Developmental Research MethodsTopic 11: Quasi Experimental Research
04/10/2023CEDP 321/322 Ryan Sain, Ph.D. 1
04/10/2023 CEDP 321/322 Ryan Sain, Ph.D.
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Quasi ExperimentationInternal vs. external validityInternal allows you to detect
effectsBut is generally low in
applicabilityExternal validity makes the study
applicableBut decreases chance to detect
effect.
04/10/2023 CEDP 321/322 Ryan Sain, Ph.D.
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Archival studiesLooking at events in history and
measuring their effect◦Looking at records◦Looking at changes before and after.
No ability to detect cause.Naturalistic observations
combined with sound data collection.
04/10/2023 CEDP 321/322 Ryan Sain, Ph.D.
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Time series designRepeated measuresTime one and time two are the
minimumCan be an experimental
treatment
04/10/2023 CEDP 321/322 Ryan Sain, Ph.D.
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Single group pre-postPre M X post MRemember – no control here – so
cannot truly conclude if the IV made the changes
Pre-test IV
Post-test
04/10/2023 CEDP 321/322 Ryan Sain, Ph.D.
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Interrupted time seriesAdding more pre and post tests Allows us to assess changes that
we cant see with a single shot.
Prior to change During Change (IV) After Change
04/10/2023 CEDP 321/322 Ryan Sain, Ph.D.
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Multiple time seriesJust like multiple but uses a
control group!No random assignment though.Adds some control – but still cant
detect cause
Prior to change During Change (IV) After Change
Prior to change After Change
04/10/2023 CEDP 321/322 Ryan Sain, Ph.D.
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Analyzing Time SeriesARIMA autoregressive integrated moving
average
Stable with consistent and noticeable changeChange in rate of changePulsing change
Prior to change During Change (IV) After Change
04/10/2023 CEDP 321/322 Ryan Sain, Ph.D.
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Non-equiv before after design
Population
Sample
Post-testIV
Pre-test
Two Group – Non Equivalent Design
Compare groups to themselves
Pretest comparison
Matching
Split known groups into two and RA
Wait Listing
04/10/2023 CEDP 321/322 Ryan Sain, Ph.D.
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Cohort Designs
Time series with cohorts ◦Can be interrupted
Cohort 2007: Track for 2 years, Monthly
Cohort 2006: Track for 2 years, Monthly
Cohort 2005: Track for 2 years, Monthly
04/10/2023 CEDP 321/322 Ryan Sain, Ph.D.
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Ex-post facto designIndividuals with certain traits are
identifiedAnalyze past experiences for
commonalitiesUse of controls
◦Year books◦Neighbors, etc
04/10/2023 CEDP 321/322 Ryan Sain, Ph.D.
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Correlational designsDesigns that are relating
variablesBut not seeking to see which
causes the otherUsed not to establish causeBut to show a relationship to then
allow for further studyPrevents us from wasting time
and resources
04/10/2023 CEDP 321/322 Ryan Sain, Ph.D.
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Naturalistic studySimply observing and describing
Darwin on the HMS Beagle◦ Started as simple observations◦ Went on to develop ideas◦ Eventually a theory◦ Now tests of that theory◦ Now it exists as a definition of life.
04/10/2023 CEDP 321/322 Ryan Sain, Ph.D.
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Naturalistic study cont.Hawthorne effect (reactance)
◦ Being observed causes changes◦ Use unobtrustive observations
Selective perception◦ We choose to focus on certain things◦ We are influenced by what we expect to see◦ Boredom – leads you to looking for boredom!
