ABSTRACT
General principles In practical terms, ‘research is often invoked as a method of establishing whether or not to provide a service, or which service to provide’ (Parry 1996). In other words, we need research to tell us which treatments are effective. This, however, is only part of the picture; we also need to know which types of behaviour a treatment is effective for, in which types of people, and which aspects of the therapeutic process are effective. In other words, research needs to look at input, outcome and process (Orlinsky and Howard 1987).
