Questionnaire in clinical research and practice.

Measurement is the means of collecting data from patients whether for purpose of research or for decision making in clinical practice. The commonest method of measurement used in research or practice is simply by observation. An obvious example is the physical examination of patients by a clinical investigator or by a doctor. Another familiar method is the use of equipment like in chemical measurement of serum creatinine or physical measurement of a patient's body weight. In this issue of MJM, there are 4 papers that utilize another type of measurement instrument, the questionnaire.