Reviewers' comments.

The large number of nonexperimental manuscripts submitted to JABA and the lack of well-defined criteria for evaluating them, has necessitated formulation of a separate editorial policy (see policy statement on page 404 of this issue). The manuscript by Alan E. Kazdin was submitted before the policy concerning nonexperimental manuscripts went into effect and was reviewed by three established researchers who have made substantial methodological contributions to the field (Montrose M. Wolf, Murray Sidman, and L. Keith Miller were Reviewers A, B, and C, respectively). On the basis of the reviewers' comments, it was decided to publish the manuscript with only minor changes. However, because of the fundamental importance of many of the issues discussed in Kazdin's paper and because of the lack of clear agreement on some of these issues, as exemplified in the reviewers' comments, these comments are presented below.