ABSTRACT
For a therapist, other than knowing his/her population, he/she also has to have an intimate knowledge of his/her service. Among the many things the therapist should know is, the referral rate to his/her service, breakdown of referral rates per individual site, breakdown of exactly where all these new patients came from, the investigations or drugs these new patients had or were prescribed, and the proportion that is classed as appropriate. It cannot be emphasised strongly enough how important these pieces of information is to the therapist. It will form the backbone of his/her baseline data, which is vital to make any credible judgement of impact into the future. Getting hold of this information should not pose too much difficulty, but, if historically the therapist has not been used to collecting certain types of information or data (patient employment information, for example), it may prove impossible to do retrospectively.
