Evaluation in prevention: implications from a general model

Evaluation is a many faceted, rapidly developing process which is held together by a common theme: A practical orientation toward using social programs. That practical orientation can be understood in three ways: as a total evaluation system, as a technological endeavor, or as a social research effort that has the intent of being useful as evaluation. There are three basic elements to good evaluation: validity, utility, and theory. Validity and utility must be understood in terms of specific threats to their integrity. The salience of those threats shifts with the context of evaluation activity. Theory is important because powerful evaluation designs cannot be developed, nor can results be interpreted, without an understanding of the dynamics of program action. Each aspect of evaluation--validity, utility and theory--must be considered relative to four aspects of prevention which pose particular impediments to the conduct of evaluation. Those special characteristics are: the need to mass target prevention programs, the problem of treating people who have not yet manifested symptoms, difficulties in ascertaining when prevention will be most useful, and the need to evaluate prevention programs with long term observation.