The Epidemiology of Cancer Therapy:  III. The Management of Imperfect Data

Anyone who has ever worked with medical records knows that they are an imperfect source of scientific data. The records contain all the idiosyncrasies and errors that can occur in the communication of human observations. Just as each patient is unique as a person and as an instance of disease, each doctor is unique in the ways he examines patients, makes decisions, and records the data; the recorded data often consist of anecdotal generalities rather than precise specifications; the statements often represent opinions or interpretations rather than descriptions of observed evidence; important information may sometimes be absent or unobtainable; and the remarks made by one doctor may sometimes contradict those made by another.

The imperfection of data in medical records is the last of a series of intellectual barriers that may make investigators reluctant to use the records as "material" in scientific research dealing with the clinical course of disease.