Controlled observations on the single case.

Valuable information can be gained from studies of a single case, provided bias on the part of physician and patient can be minimized. Use of the double-blind method achieves this. Some pitfalls in such studies are mentioned, and it is emphasized that skill, judgment and knowledge all play a part in the design and interpretation of investigations of this nature. As an example, a trial of three analeptics in the treatment of a narcoleptic patient, using a simple rating scale, is described.