Shepherd/Linn, Behavior and Classroom Management in the Multicultural Classroom
Chapter 11
Single-Subject Design
Purpose of Single-Subject Design
• The strategies included in behavior intervention plans, in particular, should be evaluated
on a continuous basis, but only a few assess the functional relationship between the
behavior and the intervention. Single-subject designs allow teachers to measure the
effectiveness of intervention strategies for the specific behavior.
Baseline Data and Intervention Data
• The first step in implementing a single-subject design is to collect and record baseline
data. Baseline data consist of information collected on the student’s target behavior, and
establishes a benchmark in which the student’s behavior can be measured.
• The baseline data can indicate whether the student’s behavior is increasing, decreasing, or
unstable; however, a stable baseline provides the best context for determining if an
intervention strategy is effective.
Level, Trend, and Variability
• Changes in the target behavior can be examined along one or more of three parameters:
level, trend, and variability.
• Level is the average rate of the behavior during a condition.
Shepherd/Linn, Behavior and Classroom Management in the Multicultural Classroom
• Variability is fluctuation in the rate of the behavior during a condition.
• Three other factors of level, trend, and variability of behavior need to be examined to
2. any overlap of data points between conditions, and
Type of Single-Subject Designs
• There are various types of single-subject designs teachers can use to measure the
effectiveness of interventions: the AB design, the withdrawal design, the alternating
treatment design, the changing criterion design, and the multiple-baseline design.
The AB Design
o The AB design because uses one set of baseline data (Condition A) and one set of
intervention data (Condition B).
o The baseline data and the intervention data are separated by the condition change line,
which is the vertical dotted line drawn upward from the abscissa (horizontal axis).
o The withdrawal design (or ABAB design) adds a second baseline after the
intervention strategy, and then reintroduces the intervention strategy after the second
baseline.
The Alternating Treatment Design
o The alternating treatment design (ABAC) is similar to the withdrawal design, but
instead of reintroducing the same intervention, the teacher adds a second, different
intervention (Condition C).
Shepherd/Linn, Behavior and Classroom Management in the Multicultural Classroom
o Baselines and interventions can be repeated often in alternating treatment designs
across multiple conditions, but each intervention should be implemented an equal
number of times.
The Changing Criterion Design
o The changing criterion design evaluates the effectiveness of an intervention strategy
by progressively increasing or decreasing the behavior in stepwise changes by
manipulating the conditions of the intervention.
o There are three factors to consider when using the changing criterion design:
The Multiple-Baseline Design
o The multiple-baseline design is an extension of the AB design that allows teachers to
examine intervention strategies across students, behaviors, and settings.
o The multiple-baseline across-behaviors design can analyze the effectiveness of an
intervention strategy on two or more behaviors of one student in a single observation
period.