QUANTITATIVE RESEARCH METHODOLOGIES

SINGLE-SUBJECT RESEARCH

ESSENTIAL CHARACTERISTICS

Data are collected and analyzed for only one subject at one time.

Most commonly used to study the changes in behavior

THE GRAPHING OF SINGLE-SUBJECT DESIGNS

Researchers primarily use line graphs to; Present their data Illustrate the effects of a particular intervention or treatment.

THE A-B DESIGN

Collecting data on the same subject, operating as his or her own control under two conditions or phases.

First condition (A); pretreatment condition

Second condition (B); treatment or intervention condition, introduced and maintained for a period of time.

figure 14.2 A-B Design.jpg

DISADVANTAGE OF A-B DESIGN

Researcher does not know whether any behavior change occurred because of the treatment.

THE A-B-A DESIGN

Sometimes called reversal design Researchers simply add another

baseline period To get stronger evidence for the

effectiveness of the intervention Reduce threats to internal validity

figure 14.3 A-B-A Design.jpg

DISADVANTAGE OF A-B-A DESIGN

It involves leaving the subjects in the A condition.

Studies ended without some degree of final improvement.

THE A-B-A-B DESIGN

Two baseline periods are combined with two treatment periods.

Permits the effectiveness of the treatment. Avoids leaving subject without an

intervention. Demonstrate that dependent variable

changes as independent variable is applied.

figure 14.4 A-B-A-B Design.jpg

DISADVANTAGES OF A-B-A-B DESIGN

The possibility of data-collector bias

An instrumentation effect; need for an extensive number of data collections period

THE B-A-B DESIGN

Involves a treatment followed by a baseline by a return to the treatment.

Appropriate when there is a lack of behavior.

figure 14.5 B-A-B Design.jpg

THE A-B-C-B DESIGN

Further modification of the A-B-A design.

The intervention is changed to control for any extra attention the subject may have received.

Contingent (or selective) praise is critical for improved responsiveness.

figure 14.6 A-B-C-B Design.jpg

MULTIPLE-BASELINE DESIGNS

Researcher do more than collect data on one behavior.

They collect on several behaviors for one subject.

Researchers systematically apply the treatment at different time for each behavior.

figure 14.8 Multiple-Baseline Design.jpg Treatment is applied to change behaviors

accordingly.

THREATS TO INTERNAL VALIDITY

1. Condition length

2. Number of variables changed when

moving from one condition to another.

3. Degree and speed of change.

4. Return to baseline level

5. Independence of behavior

6. Number of baseline

THINGS TO PONDER

Which do you think is easier to conduct: single subject or group comparison research? Why?

What sorts of behaviors might require only a few data points to establish a baseline?