*

*

Experimental and Quasi-Experimental Research

KNES 510

Research Methods in Kinesiology

*

*

Experimental Research Tries
to Establish Cause and Effect

Selection of a good theoretical frameworkApplication of appropriate experimental designUse of correct statistical model and analysisProper selection and control of independent variablesAppropriate selection and measurement of dependent variablesCorrect interpretation of results

*

*

Three Criteria for Cause and Effect

The cause must precede the effect in time

The cause and effect must be correlated with each other

The correlation between cause and effect cannot be explained by another variable

*

*

Reviewing Important Terms

Independent variableDependent variableCategorical variable-(age, sex=not controlled)Control variable-excludeExtraneous variable

*

*

Types of Validity

Internal validityExternal validityTrade-off between internal and external validitySeries of experiments (studies)

*

*

Threats to Internal Validity

History-duringMaturationTestingInstrumentationStatistical regressionSelection bias

*

*

Threats to Internal Validity, contd

Experimental mortalitySelection-maturation interactionExpectancy

*

*

Threats to External Validity

Reactive or interactive effects of testingInteraction of selection biases and treatmentReactive effects of experimental arrangementsMultiple-treatment interference

*

*

Controlling Threats to
Internal Validity

Randomization

Real randomization

Matched pairs (but not matched groups)

Randomizing treatments or counterbalancing

PlacebosBlind setupsDouble-blind setups

*

*

Uncontrolled Threats to
Internal Validity

Reactive effects of testingInstrumentationExperimental mortality

*

*

Controlling Threats to External Validity

Selecting from larger population

Participants

Treatments

Situations

Ecological validity-emulates the real world.

*

*

Types of Designs:
Pre-experimental Designs (invalid)

One-shot studies

TO

One-group pretest-posttest

O1TO2Statistical analysis? Dt

Static group comparison (one shot w/2 groups)

TO1

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

O2

*

Types of Designs:
True Experimental Designs

Randomized-groups design

RTO1Statistical analysis? It

RO2

Extending the levelsrandomized-groups design

RT1O1Statistical analysis? Ab

RT2O2

RO3

*

Types of Designs:
True Experimental Designs, contd

-1 interaction

-2 main effects

*

Types of Designs:
True Experimental Designs, contd

A factorial design with a categorical factor (B)

RA1O1

B1RA2O2

RA3O3Statistical analysis? M

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

RA1O4

B2RA2O5

RA3O6

Types of Designs:
True Experimental Designs

Pretest-posttest randomized-groups

RO1TO2

RO3 O4Statistical analysis? MFA

Extending the design on the RM factor

RO1TO2 TO3 Statistical analysis? MFA-RM

RO4O5O6

*

*

Types of Designs:
True Experimental Designs, contd

Extending the pretest-posttest randomized groups design on both factors

RO1T1O2T1O3

RO4T2O5T2O6

RO7O8O9

Statistical analysis? AN (covariate)

*

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.

*

Quasi-Experimental Designs:
Reversal (return to baseline)

*

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.

TO1

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

O2

*

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 participants response become less variable over treatment times?

*

Quasi-Experimental Designs:
Single Participant, contd

Is participants magnitude of response sensitive to multiple treatment applications?Do varying intensities, frequencies, and lengths of treatment produce varying responses?

Next Class

Chapter 15Abstracts tonightResearch Q?List of 10 references3 intro paragraphs

Rationale

Lit summary

Show the missing brick, purpose and hypotheses

*