Most children with autism make substantial progress and gain valuable skills and independence when education and treatment based on ABA are applied.  Though ABA has been shown to be effective, many of the aspects of applying the principles of behavior analysis in the treatment of autism have not been investigated thoroughly. For example, how many hours per week are necessary to produce a change is not known. Additionally, some skills are very difficult to teach and the best instructional strategies are not known. It is, however, quite likely that the proficiency of the providers of service, both direct care therapists or teachers and their supervisors will play a significant role in the progress that any child makes.