systems and state and federal programs. The committee applied strict standards to assess the quality of the large body of information that it assembled. The committee considered arguments of legal rights and documentation of public policy, and current practices in well-established programs, as well as empirical data concerning the effectiveness of various techniques. Within its evaluation of the current scientific literature, the committee’s goal has been to interpret findings as broadly as possible in terms of their implications for early educational practices, while retaining scientific integrity and perspective in considering the strengths and limitations of various bodies of work.

Committee’s Process for Evaluating Evidence

Science is a systematic way of gathering, analyzing, and assessing information. One of the strengths of the field of autism is the many disciplines and areas of scientific inquiry within which it has been addressed. The committee’s approach was to gather information from as wide a range of sources as possible, to assess the strengths and limitations of different sources of information, and to assess the results with an eye toward convergence, particularly from independent sources, of descriptive data, inferential data, and theory.

For example, within the field of autism, there are many approaches to intervention that are widely disseminated but little researched. Some approaches have been greeted with great enthusiasm initially, but have relatively quickly faded out of general use, in part because of their failure to demonstrate worthwhile effects. Other approaches have withstood the test of time across sites and the children and families they serve, though they continue to be largely supported by clinical descriptions of effectiveness, rather than by formal evaluations. Yet wide use and respect cannot be interpreted as clear evidence of effectiveness; therefore, the committee elected to consider information about these approaches in light of more empirically oriented studies.

To achieve a systematic and rigorous assessment of research studies, the committee established guidelines for evaluating areas of strength, limitations, and the overall quality of the evidence; these guidelines are presented in Box 1–1. They are based on approaches used by scientific societies and in recent publications, including: the American Academy of Neurology (Filipek et al., 2000); the American Psychological Association (American Psychological Association, 2000; Barlow, 1996; Chambless and Hollon, 1998); the Society for Clinical Child Psychology (Lonigan et al., 1998); and the New York State Department of Health (1999). A number of comprehensive reviews concerning early intervention in autism also provided examples of ways to systematize information (Dawson and Osterling, 1997; Howlin, 1998; Rogers, 1998; Rumsey et al., 2000). These



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