Measurement in clinical trials.

Measurement is the delimitation and fixation of our ideas upon things.It appears to be necessary for answering questions about the order of our environ- ment and particularly for that form of questioning we call experiment.Not only is it necessary to know what is to be measured but also why it is to be measured so that the instruments may be appropriately chosen and the results presented in a useful form.Measurement is not a process of discovery but a tool for sorting observations according to preconceived rules.It is apparent that not everyone operates the same rules, so there will be disagreement about what has been observed.This is an accepted and generally enjoyable fact of individual existence.However much human action is organised, concerted and applied to common tasks.Conflicting individual practices must therefore be resolved if these tasks are to be accomp- lished efficiently.This paper aims to identify the major issues concerning measurement in clinical trials and indicate the direction in which solutions may be found.To avoid confusion two words will be given defined