Research on suicide is plagued with many methodological problems that limit progress in the field. Definitions lack uniformity, proximal measures are not always predictive of suicide, reporting of suicide is inaccurate, and its low frequency exacerbates all of these problems.


There is a need for researchers and clinicians in suicidology to use a common language or set of terms in describing suicidal phenomena. Thirty years ago, NIMH convened a conference on suicide prevention at which a committee was charged with recommending a system for defining and communicating about suicidal behaviors (Beck et al., 1973). As a result of this committee’s work, operational definitions for basic terms such as suicidal ideation, suicide attempts, and completed suicide were proposed. Definitional issues were revisited in the mid-1990s at workshops held by the American Association of Suicidology, NIMH, and the Center for Mental Health Services, and through informal discussions among suicidologists (O’Carroll et al., 1996). Once again, the difficulties caused by lack of efficient communication and cross-talk were described, and a specific nomenclature with objective definitions of suicidal behaviors was proposed. Interestingly, many of the definitions proposed in this article were not appreciably different from those proposed for researchers more than a quarter of a century ago by the NIMH committee. Despite this seeming consensus, terminology continues to be an obstacle (see also Chapter 1). For example, “suicide attempt” does not uniformly include the intent to die. Since some who harm themselves do not actually intend to die (Linehan, 1986), assessing suicidal behavior is difficult. Not only are terms used differently across the field, they only infrequently are operationally defined in studies. Furthermore, often researchers do not reliably assess behavioral intent, since interviews can be unreliable (Linehan, 1997). Comparisons across studies also are complicated by differences in scales and instruments used to measure suicidality (see also Chapter 7). Many studies use only selected questions from questionnaires instead of the complete validated tool. Many of the studies do not report validity and reliability of instruments used.

Low Base-Rate Event

The base-rate of completed suicide is sufficiently low to preclude all but the largest of studies. When such studies are performed, resultant comparisons are between extremely small and large groups of individu-

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