Some problems associated with the measurement of community psychiatric nurse intervention *

This paper describes a study that was originally proposed to evaluate community psychiatric nurse intervention in terms of client outcome. Although the literature indicates the strong need for research of this nature, the strategy that it demands poses formidable methodological problems. These diffculties are examined within the framework of Campbell & Stanley's (1963) concept of‘internal validity’. Although the proposed design is assessed to be weak, it is argued that stringent appraisal of method can only strengthen the nursing profession's claim to produce research that is both credible and relevant.