Question

In 150- 200 words, describe different single subject case designs

a. Describe AB, ABA, ABAB, multiple baseline, and alternating treatments design

b. Give an example of how you could use this design

c. Pick two designs to compare. Why would you choose one design over the other?

Answer 1

A-B design

The A-B design is the basic single-subject design. It includes a baseline phase with repeated
measurements and an intervention phase continuing the same measures. Take, for example,
two parents who are having problems with one of their children. Meeting with their social
worker, they complain that, over the last month, their 16-year-old daughter has been squab-
bling constantly with her brother and being rude and sarcastic with her parents. The social
worker suggests that the parents use a point system, with points being accrued for poor
behavior. Once a certain number of points are attained, the child will begin to lose certain
privileges. To test the intervention, the parents are instructed to count and record every 3
days over a 15-day period the number of instances of sibling arguments begun by the child
and the number of rude and sarcastic comments. The intervention begins on the 16th day,
with the parents explaining how the child might get negative points and face the conse-
quences of accumulating points.

ABA design

The A-B-A design builds on the A-B design by integrating a posttreatment follow-up that
would typically include repeated measures. This design answers the question left unan-
swered by the A-B design: Does the effect of the intervention persist beyond the period in
which treatment is provided? Depending on the length of the follow-up period, it may also
be possible to learn how long the effect of the intervention persists.

ABAB design

The A-B-A-B design builds in a second intervention phase. The intervention in this phase is iden-
tical to the intervention used in the first B phase. The replication of the intervention in the sec-
ond intervention phase makes this design useful for social work practice research. For example,
if, during the follow-up phase, the effects ofthe intervention began to reverse then the effects of the intervention can be established by doing it again. If there is a second improvement, the replication reduces the possibility that an event or history explains the change.

Multiple baselines

In the withdrawal designs, the individual serves as the control for the impact of the interven-
tion. Yet the withdrawal designs suffer from the problem that often the target behavior can-
not be reversed, and it may not be ethical to withdraw treatment early. A solution to these
problems is to add additional subjects, target problems, or settings to the study. This method
provides social work researchers with a feasible method of controlling forthe effects of history.

ATD

The alternating treatment design (ATD) consists of rapid and random or semirandom alteration of two or more conditions such that each has an approximately equal probability of being present during each measurement opportunity. As an example, it was observed during a clinical training case that a student therapist, during many sessions, would alternate between two conditions: leaning away from the client and becoming cold and predictable when he was uncomfortable, and leaning towards the client and becoming warm and open when feeling comfortable. The client would disclose less when the therapist leaned away, and more when he leaned forward. If it were assumed that the therapist had preplanned the within-session alternations, an ATD as shown in Figure 6 would be obtained. The condition present in the example at any given time of measurement is rapidly alternating. No phase exists; however, if the data in each respective treatment condition are examined separately, the relative level and trend of each condition can be compared between the two data series .