1. Professionals who are not trained in the scientific method as it applies to individuals are trained instead in studies that examine the effects of treatments on large groups of individuals, typically following the logic i shown in Figure 1. In this figure the goal is to make a decision about which of two drugs should be regarded as most effective. The drug is given to individuals in each group, the results averaged, and then the group average that shows the best improvement is the one that is regarded as the treatment of choice. To ensure that there is no bias in terms of the makeup of the groups, individual allocation to each group is randomized.
Figure 1
Figure 1:
Panel a — In an idealized group design, a treatment drug (Left-hand side) is given to a large number of participants in which variability between them is minimal. The control drug is given to a similar group of participants (Right-hand side).

Panel b — Because an idealized group does not exist, participants for each group are randomly assigned to minimize the effects of extraneous variables that unexpectedly contribute to any differences between group results (Randomized Control Trial).

Panel c — Variability in individual responses that arise because of the effects of the drug, and/or variability in individual histories are represented by the spectrum.

2. However, ABA emphasizes the careful study of each individual who receives intervention. Figure 3 (based on Reese, 1978) gives an overview of how the scientific method is used in the study of individuals. As you can see, the overall goal is to adapt known principles of behavior (laws of learning) to the needs of the individual and to continuously monitor changes in the behavior of the individual to maximize the benefit to that individual. This approach is fundamental to getting it right for the individual, whatever length of time it takes. And because adjustments are tailor-made for each individual, the opportunities for learning are maximized for each individual. How far each individual can progress depends on many factors, but focusing on the individual in such a fine-grained way, using known principles of behavior, is to be preferred to developing an intervention that is based on a group average and that is insensitive to the needs of the individual.

Figure 2:
The scientific method used in ABA provides a clear alternative to scientific method associated with RCTs when it comes to developing tailor-made procedures for producing and monitoring changes in an individual.

In conclusion, parents need to be aware of how conflict in scientific traditions affects policy decisions. When the evidence for using single-case designs is properly understood, a science that uses it can be seen to offer parents the best hope for their children (Green, 2008).

Green, G. (2008). Single-case research methods for evaluating treatments for autism spectrum disorders. Opportunities... Hope... Potential... The future of Pennsylvania, Autism in Pennsylvania: What lies ahead, 8, 69-81.

Keenan, M. & Dillenburger, K. (2011). When all you have is a hammer...: RCTs and hegemony in science. Research in Autism Spectrum Disorders, 5, 1-13.

Reese, E. (1978). Human operant behavior: Analysis and application. Brown & Benchmark.