A New Phase and Mastery
Register by January 19th, or email firstname.lastname@example.org to register after that date.
Baseline - September
Intervention - October/November
47 minutes avg
27 minutes avg
Final Phase - December
Fading reinforcement from every time to every other time is a great way to gain independence!
"The baseline phase (abbreviated by the letter A) represents the period in which the intervention to be evaluated is not offered to the subject. During the baseline phase, repeated measurements of the dependent variable are taken or reconstructed. These measures reflect the status of the client (agency or community) on the dependent variable prior to the implementation of the intervention. The baseline phase measurements provide two aspects of control analogous to a control group in a group design. First, in a group design, we expect the treatment group to have different scores than the control group after the intervention. In a single-subject design, the subject serves as the control as the repeated baseline measurements establish the pattern of scores that we expect the intervention to change. Without the intervention, researchers assume that the baseline pattern of scores would continue its course. Second, in a control group design, random assignment controls for threats to internal validity. In a single-subject design, the repeated baseline measurements allow the researcher to discount most threats to the internal validity of the design.
The treatment phase (signified by the letter B) represents the time period during which the intervention is implemented. During the treatment phase, repeated measurements of the same dependent variable using the same measures are obtained. Ultimately, the patterns and magnitude of the data points are compared to the data points in the baseline phase to determine whether a change has occurred. Tony Tripodi (1994) and David Barlow and Michel Hersen (1984) recommend that the length of the treatment phase be as long as the baseline phase."
Later on, the authors provide some examples utilizing A and B to describe single case research designs utilized in behavior analysis:
"Basic Design (A-B) 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 squabbling 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 consequences of accumulating points.
Withdrawal Designs There are two withdrawal designs: the A-B-A design and the A-B-A-B design. By withdrawal, we mean that the intervention is concluded (A-B-A design) or is stopped for some period of time before it is begun again (A-B-A-B design). The premise is that if the intervention is effective, the target problem should be improved only during the course of intervention, and the target scores should worsen when the intervention is removed. If this assumption is correct, then the impact of an extraneous event (history) between the baseline and intervention phase would not explain the change.
This premise, however, is problematic for social work research. Ideally, the point of intervention is to reduce or eliminate the target problem without the need for ongoing intervention. We would like the impact of the intervention to be felt long after the client has stopped the intervention. Practice theories, such as behavioral or cognitive behavioral treatment, are based on the idea that the therapeutic effects will persist. This concern, referred to as the carryover effect, may inhibit the use of these designs. To be used for research, the implementation of each of the withdrawal designs may necessitate limiting the length of the intervention and ending it prematurely. If the designs are being used for evaluation, it is unnecessary to prematurely withdraw the intervention; rather, the second baseline provides important follow-up information.
Multiple Baseline Designs In the withdrawal designs, the individual serves as the control for the impact of the intervention. Yet the withdrawal designs suffer from the problem that often the target behavior cannot 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. The basic format is a concurrent multiple baseline design, in which a series of A-B designs (although A-B-A or A-B-A-B designs could also be used) are implemented at the same time for at least three cases (clients, target problems, or settings). Therefore, the data are collected at the same time. The unique feature of this design is that the length of the baseline phase is staggered...to control for external events (i.e., history) across the three cases. The baseline phase for the second case extends until the intervention data points for the first case become more or less stable. Similarly, the intervention for the third case does not begin until the data points in the intervention phase for the second case become stable. The second and third cases act as a control for external events in the first case, and the third case acts as a control for the second case."