Macarthur Violence Risk Assessment Study

Identifying Gaps in Methodology

Almost all existing studies of violence risk assessment suffer from one or more methodological problems: They considered a constricted range of risk factors, often a few demographic variables or scores on a psychological test; they employed weak criterion measures of violence, usually relying solely on arrest; they studied a narrow segment of the patient population, typically males with a history of prior violence; and they were conducted at a single site. Based on this critical examination of existing work, the MacArthur researchers designed a piece of research that could, to the greatest extent possible, overcome the methodological obstacles that had been identified. They studied a large and diverse array of risk factors. They triangulated the outcome measurement of violence, adding patient self-report and the report of a collateral informant to data from official police and hospital records. They studied both men and women, regardless of whether they had a history of violence. And they conducted the study at several sites rather than at a single site.

Selecting Promising Risk Factors

Although the MacArthur researchers lacked any comprehensive theory of violence by people with mental disorder from which they could derive hypothesized risk factors, recent studies suggested that a number of variables might be potent risk factors for violence among people with a mental disorder. The researchers assessed personal factors (e.g., demographic and personality variables), historical factors (e.g., past violence and mental disorder), contextual factors (e.g., social support and social networks), and clinical factors (e.g., diagnosis and specific symptoms). They chose what they believed to be the best of the existing measures of these variables, and where no instrument was available to adequately measure a variable, they commissioned the development of the necessary measure.

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