Order #403985 Topic: #3

Assignment

Posttest (2-week delay)

Chapter_4.pptx

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An Applied Reference Guide to Research Designs Quantitative, Qualitative, and Mixed Methods

A Visual System for Research Designs in

Education and the Social & Behavioral Sciences

Edmonds, W. A., & Kennedy , T. D. (2012). An applied reference guide to research designs: Quantitative, qualitative, and mixed methods. Thousand Oaks, CA: Sage.

Ch. 4

Within-Subjects Approach

Sage Publications

Within-subjects Approach

Good alternative to between-subjects when:

Access to participants is limited

Random assignment is not possible

The primary goal with this approach is that each subject or group is exposed to each of the treatment conditions

More threats to internal validity are associated with this approach:

Maturation

History

Sequencing Effects

Within-subjects Approach

Also referred to as repeated-measures approach

Allows for the collection of multiple data points over time

Most basic design is the one-group pre and posttest design

Interrupted Time-series Design

Crossover Design (k-factor design for repeated measures)

Experimental Research for the repeated measures approach

These designs can be designated as experimental research (cause-effect) so long the following can be ensured:

Covariation?

Temporal Precedence?

No Plausible Alternative Explanation?

Major Threat to internal validity

Sequencing Effects

Sequencing Effects is addressed through counterbalancing

Repeated-measures plus between-subjects

Some designs within the repeated-measures approach include between-subjects components

Switching replications design

2-group pre- and posttest design (with multiple posttests)

The emphasis can be on both the within- and between-subjects variances

This is determined theoretically

Common variants

Crossover Design

Minimum 2 factors

Can include individuals or groups

Interrupted Time-series Design

Should include at least 10 observation points but many times should be more (theoretically determined)

Latin-square design

Complex one-factor design

Rarely applied in social sciences

Subject	Treatment	Midtest	Treatment	Midtest	Treatment	Posttest
1	XA	O1	XB	O2	XC	O3
2	XB	O1	XC	O2	XA	O3
3	XC	O1	XA	O2	XB	O3
4	XC	O1	XB	O2	XA	O3
5	XA	O1	XC	O2	XB	O3
6	XB	O1	XA	O2	XC	O3
Time ►

Most common threats

Most common threats to internal validity related, but not limited, to these designs:

Experimental. History, Maturation, Testing, Instrumentation, Attrition, and Sequencing Effects.

Quasi-experimental. History, Maturation, Testing, Instrumentation, Statistical Regression, Selection Bias, Attrition, and Sequencing Effects.

Pretest and Multiple-posttest Design

Research Question Example Here: Fill in the blanks

Formulate a RQ which would necessitate the use of this type of design

Group	Pretest	Treatment	Posttest1	Posttest2
1	O1	X	O2	O3
2	O1	-	O2	O3
Time ►

Pretest and Multiple-posttest Design

What are the general weaknesses (in terms of internal validity) of this design?

How can group equivalency be tested?

How much time should elapse between posttests?

Should the emphasis be on the within- or between-subject variances?

Switching-replications Design

Research Question Example Here: Fill in the blanks

Assignment	Group	Pretest (Baseline)	Treatment	Midtest (3 months)	Treatment	Posttest (6 months)
					-
			-
Time ►

Group	Pretest	Treatment	Midtest	Treatment	Posttest
1	O1	XA	O2	-	O3
2	O1	-	O2	XA	O3
Time ►

Switching-replications Design

What are the general weaknesses (in terms of internal validity) of this design?

How can group equivalency be tested?

Should there be a certain amount of time that should elapse before the next groups receives the intervention? Why or why not?

Crossover Design

Research Question Example Here: Fill in the blanks

Group	Pretest	Treatment	Midtest	Treatment	Posttest
1	O1	XA	O2	XB	O3
2	O1	XB	O2	XA	O3
Time ►

Sage Publications

Crossover Design

What are the general weaknesses (in terms of internal validity) of this design?

How can group equivalency be tested?

How could sequencing effects affect the outcome?

Should the emphasis be on the within- or between-subject variances?

Interrupted time-series design

Research Question Example Here: Fill in the blanks

Group	Pretests	Treatment	Posttests
1	O1…O6	X	O7…O11
2	O1…O6		O7…O11
Time ►

Assignment	Group	Observations	Treatment	Observations


Time ►

Interrupted time-series design

What are the general weaknesses (in terms of internal validity) related to this design?

What are the strengths (in terms of internal validity) of this design because of the removal of the pretest?

Is it advisable to utilize non-random assignment with this design? Why or Why not?

How many observations should be taken prior to and after the intervention (or major event)?

Access companion website to further explore specific references of interest

http://www.sagepub.com/edmonds/

Be cautious of internet resources on research design and methodology.

Be aware that many books use different types of terminology to explain the same thing.

Group 1

Group 2

Group 1

Group 2