Change and many complex issues associated with change are of central interest in this small book—the product of eight years of work by a Group for the Advancement of Psychiatry (GAP) committee. How to correctly evaluate change, ie, treatment of stimulus effects, is a current problem among behavioral scientists, and also a recurring problem, as it manifests itself in all research involving manipulation of conditions. Certainly it is an important problem, and any book which clarifies topics relevant to an important problem should be commended; likewise, any book which confuses such topics should be disapproved. By these standards, the book under consideration deserves both praise and criticism.
The hope of the authors is expressed in the introduction with these words. "Since the assessment of change is a major daily concern of practitioners, teachers, and administrators, as well as researchers, we hope that this report