The dropout and the terminator: a methodological note on definitions.

The numerical criteria of either mean or median number of sessions as a nethodological procedure for categorizing patients as dropouts were compared with the clinically based definition in a sample of 221 outpatients. Lack of agreement was noted in two primary areas. A large number of clinically defined terminators were classified incorrectly as dropouts, and a large number of clinically defined dropouts were not classified when the mean or median number of sessions was used as a criterion to classify the dropout. The results of the study supported the contention that definitions of dropping out based on number of sessions lead to categorizations that are not comparable to those based on knowledge of the clinical data.