Metaphorical analysis of psychiatric classification as a psychological test.

In this taxonomic article we explore the metaphor of comparing a psychiatric classification to a psychological test. Structurally, diagnostic criteria are like test items; diagnostic categories are like scales; and classification are like tests. Analytically, the ideas of reliability and validity are the primary concepts invoked in the empirical evaluation of both classifications and tests. However, when the metaphor is explored in more detail, the differences between classifications and tests become clear. These differences are discussed in terms of the structural and analytical relations between tests and classifications. This metaphorical analysis of classifications as tests suggests that certain issues that have been discussed in regard to psychological tests, particularly reliability and validity, may require modification when applied to psychiatric classification.