Single- Subject Research Designs Chapter 14

Single- subject designs Single- subject designs, or single- case designs, are research designs that use the results from a single participant or subject to establish the existence of cause- and- effect relationships.

Phases and phase changes A phase is a series of observations of the same individual under the same conditions. When no treatment is being administered, the observations are called baseline observations.

Visual Inspection Techniques Unfortunately, there are no absolute, objective standards for determining how much of a change in pattern is sufficient to provide a convincing demonstration of a treatment effect. The most convincing results occur when the change in pattern is immediate and large.

4 types of change Change in average level Immediate change in level Change in trend Latency of change.

Change in average level Change in trend Immediate change in level Latency in Change

The problem with single subject design

THE ABAB REVERSAL DESIGN the majority of single- subject research studies use ABAB design; consists of four phases: a baseline phase ( A), followed by treatment ( B), then a return to baseline ( A), and finally a repetition of the treatment phase ( B).

Effective A= no treatment

Not Effective

Variations on the ABAB Design

1- B&B1 not working use C

2- B not working add C B= Graduated exposure C= Reinforcement

3- MULTIPLE- BASELINE DESIGNS 1- Eliminates the need for a return to baseline and therefore, 2- Is particularly well suited for evaluating treatments with long- lasting or permanent effects.

3- MULTIPLE- BASELINE DESIGNS Examples A therapist uses the same method for 2 different behaviors (across behaviors) For one behavior that is exhibited in 2 different situations. (across situations) A teacher uses the same method on 2 different individuals (across subjects)

Person1 Person2 2 different students

Yelling Crying 2 different behaviors

School Home 2 different situations.

Weaknesses of the Multiple- Baseline Design? a treatment applied to one behavior may generalize and produce changes in the second behavior. one behavior may show a large and immediate change, but the second behavior may show only a minor or gradual change when the treatment is introduced one INDIVIDUAL may show a large and immediate change, but the second behavior may show only a minor or gradual change when the treatment is introduced

4- Dismantling design A dismantling design, also called a component- analysis design, consists of a series of phases in which each phase adds or subtracts one component of a complex treatment to determine how each component contributes to the overall treatment effectiveness.

Example

5- The Changing- Criterion Design The criterion level is changed from one phase to the next.

Smoking Treatment

6-The Alternating- Treatments Design In an alternating- treatments design, also called a discrete-trials design, two ( or more) treatment conditions are randomly alternated from one observation to the next.

Example - Alternate weeks

Group Discussion Suppose you are interested in performing an observational study of kindness (kind behavior) among students in a school. Describe one method to quantify this behavior: that is, explain how you could convert the observations into numerical scores. In most research studies, statistical techniques are used to rule out chance as a plausible explanation for the results. In single-subject research, how is chance (or coincidence) ruled out as a plausible explanation for the observed treatment effects?​