The variability of presentation and progression among children with autism spectrum disorders, as well as potential differences in delivery of behavioral interventions, make this topic challenging to study. Nevertheless, given the importance of caring for children with ASD, additional research is needed to identify those characteristics of treatment—content, technique, intensity, starting and ending age, etc.—that maximize its effectiveness. Because of the challenges in launching a very large randomized trial and the ethical necessity to provide some treatment to the control group, this body of research needs to be built piece by piece, with a series of studies that investigate different components of the larger research question. For this to be effective, however, the overall quality of studies needs to be improved, including a greater emphasis on randomized, controlled trials, where at all possible; substantially larger sample sizes; uniformity of outcomes evaluated and instruments used to measure them; and consistent treatments that do not vary widely within treatment groups (i.e., experimental or control group).
The cost of continuing the current course of assuming that EIBI works may not be obvious. EIBI is costly financially for society and requires a large time commitment from children, their families, and their teachers or therapists. However, these programs may not appear to pose any harm for the children themselves. Nevertheless, the opportunity costs could be high, indeed, of providing suboptimal care to these children, simply because we as a society do not know what works best. The children may be treated with an intervention that is not as effective as the alternatives. And if we accept an intervention because it seems to work, without solid evidence, research on the alternatives or on how it can be improved is likely to be stifled.