Single-Subject Research

Advantages of Single-Subject Research Methods

• Useful for:– behavior modification research– diagnosing teaching and learning problems– studying classroom management methods– development of students’ skills

Advantages of Single-Subject Research Methods (2)

• Useful for:– training studies with special needs students– studying a problem in great detail– functioning simultaneously as teacher and

researcher (action research)

PROCEDURES USED TO ACHIEVE EXPERIMENTAL CONTROL IN SINGLE SUBJECT RESEARCH

DESIGNS

• Multiple, reliable observations of student behavior• Detailed description of the treatment (IV)• Replication of the treatment effects (across

subjects, settings, and/or behaviors)

Procedures for obtaining reliable observations of behaviors

• Operational definition of to-be-observed (target) behaviors

• Careful training of observers

• Frequent checks of observer reliability

• Control of observer bias

Single-Subject Research Designs

Basic to all single-subject research is “A-B” logic:

• Condition A: environmental conditions are constant; target behavior is observed to occur at consistent, stable rate.

• Condition B: one of the environmental conditions changes and there is a corresponding change observed in the target behavior.

Logical inference: The change in environmental conditions had something to do with the observed change in behavior; if we can assume that the behavior would have remained at its stable rate as long as Condition A remained in effect.

Change in environment: the “treatment”

Research Designs

• A-B design

• A-B-A design

• Multiple baseline designs:– A-B-A-B design– B-A-B design– A-B-C-B design

• (“C” is a 2nd, different treatment.)

Problems with the A-B design:

• Low in internal validity

• Cannot attribute observed changes in the target behavior to the treatment

• Other factors may be responsible for observed changes in behavior

• Use only when no suitable alternative is available (or for pilot study)

Problems with A-B-A design

• Sometimes behaviors that are “treated” during the treatment phase (B) do not return to baseline because the behaviors cannot be “unlearned” or reversed.

• Therefore, it is difficult to show that the treatment has, in fact, brought about the observed change in behavior.

A Multiple Baseline Design

Behavior:

1 0 0 0 0 0 X 0 X 0 X 0 X 0 0

2 0 0 0 0 0 0 0 0 0 0 X 0 X 0 X

3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 X 0

Multiple Baseline Designs

• Multiple baseline designs are used when:– you cannot withdraw or reverse a treatment, or

– you cannot demonstrate a treatment effect with an A-B-A design

MBD across behaviors

• (1) Take baseline measure on two or more behaviors of one student.

• (2) Treatment is applied to Behavior A after baseline stabilizes.

• (3) After observed change in Behavior A occurs, treatment is applied to Behavior B.

MBD across situations

• (1) one behavior of one student is observed across two or more situations (e.g., classroom, playground);

• (2) after baseline rates stabilize in setting 1, treatment is applied;

• (3) after behavior changes in setting 1, treatment is then applied in setting 2.

MBD across individuals

• (1) a problem behavior of two students is targeted for treatment

• (2) after baseline rate of the behavior of student A stabilizes, the treatment is applied to Student A;

• 3.) after Student A behavior is observed to change, the treatment is then applied to Student B.

Various combinations of these MBDs can be used:

• MBD across behaviors and situations

• MBD across behaviors and individuals

• MBD across situations and individuals

• MBD across behaviors, situations, and individuals

Sometimes, multiple, and different treatments can be used in the same single-subject design.

Sometimes, single-subject research begins with the

treatment phase, followed by a baseline phase, and then a

second treatment phase (B-A-B) design

Wood, Frank, & Wacker (1998).

“Teaching multiplication facts to students with learning disabilities”

Single subject study...

• Example of multiple-baseline across subjects and across behaviors research.

• Allowed investigators to determine if– simple practice increases student learning– instruction generalizes to other multiplic. facts

• Purposes: (1) improve students’ multiplication skills; (2) evaluate efficacy of instructional program.

Students taught four skills:

• Ask selves a question about multiplication problem;

• problem-solving strategy;

• mnemonic strategy (key-word method);

• attribution of success to correct use of strategies.

Visual analysis

vs.

Statistical analysis