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Experimental and Quasi-Experimental and Quasi-Experimental ResearchExperimental Research

KNES 510KNES 510

Research Methods in Research Methods in KinesiologyKinesiology

22

Experimental Research TriesExperimental Research Triesto Establish Cause and Effectto Establish Cause and EffectSelection of a good theoretical frameworkSelection of a good theoretical frameworkApplication of appropriate experimental Application of appropriate experimental designdesignUse of correct statistical model and analysisUse of correct statistical model and analysisProper selection and control of independent Proper selection and control of independent variablesvariablesAppropriate selection and measurement of Appropriate selection and measurement of dependent variablesdependent variablesCorrect interpretation of resultsCorrect interpretation of results

22

33

Three Criteria for Cause and Three Criteria for Cause and EffectEffect

1.1. The cause must precede The cause must precede the effect in timethe effect in time

2.2. The cause and effect must The cause and effect must be correlated with each be correlated with each otherother

3.3. The correlation between The correlation between cause and effect cannot be cause and effect cannot be explained by another explained by another variablevariable

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Reviewing Important TermsReviewing Important Terms

Independent variableIndependent variable

Dependent variableDependent variable

Categorical variable-(age, sex=not controlled)Categorical variable-(age, sex=not controlled)

Control variable-excludeControl variable-exclude

Extraneous variableExtraneous variable

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Types of ValidityTypes of ValidityInternal validityInternal validity

External validityExternal validity

Trade-off between internal and external validityTrade-off between internal and external validity

Series of experiments (studies)Series of experiments (studies)

55

66

Threats to Internal ValidityThreats to Internal Validity

History-duringHistory-during

MaturationMaturation

TestingTesting

InstrumentationInstrumentation

Statistical regressionStatistical regression

Selection biasSelection bias

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Threats to Internal Validity, cont’dThreats to Internal Validity, cont’d

Experimental mortalityExperimental mortality

Selection-maturation interactionSelection-maturation interaction

ExpectancyExpectancy

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Threats to External ValidityThreats to External ValidityReactive or interactive effects of testingReactive or interactive effects of testing

Interaction of selection biases and treatmentInteraction of selection biases and treatment

Reactive effects of experimental arrangementsReactive effects of experimental arrangements

Multiple-treatment interferenceMultiple-treatment interference

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99

Controlling Threats toControlling Threats toInternal ValidityInternal Validity

RandomizationRandomization– Real randomizationReal randomization– Matched pairs (but not matched groups)Matched pairs (but not matched groups)– Randomizing treatments or counterbalancingRandomizing treatments or counterbalancing

PlacebosPlacebos

Blind setupsBlind setups

Double-blind setupsDouble-blind setups

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Uncontrolled Threats toUncontrolled Threats toInternal ValidityInternal Validity

Reactive effects of testingReactive effects of testing

InstrumentationInstrumentation

Experimental mortalityExperimental mortality

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Controlling Threats to External Controlling Threats to External ValidityValidity

Selecting from larger populationSelecting from larger population– ParticipantsParticipants– TreatmentsTreatments– SituationsSituations

Ecological validity-emulates the real world?Ecological validity-emulates the real world?

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Types of Designs: Pre-experimental Designs (invalid)

One-shot studiesT O

One-group pretest-posttest

O1 T O2 Statistical analysis? Dt

Static group comparison (one shot w/2 groups)

T O1

--------------- Statistical analysis? It

O2

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Types of Designs:True Experimental Designs

Randomized-groups design

R T O1 Statistical analysis? It

R O2

Extending the levels—randomized-groups design

R T1 O1 Statistical analysis? Ab

R T2 O2

R O3

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Types of Designs:True Experimental Designs, cont’d

-1 interaction-2 main effects

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Types of Designs: True Experimental Designs, cont’dA factorial design with a categorical factor (B)

R A1 O1

B1 R A2 O2

R A3 O3 Statistical analysis? M

----------------------------

R A1 O4

B2 R A2 O5

R A3 O6

Types of Designs:Types of Designs:True Experimental DesignsTrue Experimental Designs

Pretest-posttest randomized-groupsPretest-posttest randomized-groups

RR OO11 TT OO22

RR OO33 OO44 Statistical analysis? MFAStatistical analysis? MFA

Extending the design on the RM factorExtending the design on the RM factor

RR OO11 TT OO22 T T OO33 Statistical analysis? MFA-RM Statistical analysis? MFA-RM

RR OO44 OO55 OO66

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Types of Designs: True Experimental Designs, cont’dExtending the pretest-posttest randomized groups design on both factors

R O1 T1 O2 T1 O3

R O4 T2 O5 T2 O6

R O7 O8 O9

Statistical analysis? AN (covariate)

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Types of Designs: True Experimental Designs, cont’d

Solomon four-group design—purpose=pretest effects

R O1 T O2

R O3 O4

R T O5

R O6

Statistical analysis (factorial ANOVA)No treatment Treatment

Pretested O4 O2

Unpretested O6 O5

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Quasi-Experimental Designs:Time Series (slope)

D.T. Campbell and J.C. Stanley, Experimental and quasi-experimental designs for research. Copyright © 1963 by Houghton Mifflin Company. Reprinted with permission.

2020

Quasi-Experimental Designs:Reversal (return to baseline)

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Quasi-Experimental Designs:Ex Post Facto (discriminate)

This is one of the pre-experimental designs, but with the treatment not under the control of the experimenter.

T O1

------------------ Statistical analysis? A

O2

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Quasi-Experimental Designs:Switched Replication

Trials

Levels 1 2 3 4 5

1 O1 T O2 O3 O4 O5

2 O6 O7 T O8 O9 O10

3 O11 O12 O13 T O14 O15

4 O16 O17 O18 O19 T O20

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Quasi-Experimental Designs:Single Participant

Identify participant and follow over time.

Does the treatment produce the same effect each time?

Are treatment effects cumulative, or does participant return to baseline?

Does participant’s response become less variable over treatment times?

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Quasi-Experimental Designs:Single Participant, cont’d

Is participant’s magnitude of response sensitive to multiple treatment applications?

Do varying intensities, frequencies, and lengths of treatment produce varying responses?

Next ClassNext Class

Chapter 15Chapter 15

Abstracts tonightAbstracts tonight

Research Q?Research Q?

3 intro paragraphs3 intro paragraphs1.1. RationaleRationale

2.2. Lit summaryLit summary

3.3. Empty space and purposeEmpty space and purpose

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