A Psychometric Evaluation of the State-Trait Anger Expression Inventory-2 for UK Adult Male Forensic Psychiatric Inpatients

Abstract

Recent reviews of clinical assessments used in the forensic mental health field have identified a need for psychometric evaluations to support their use. The current study tested the 6 factor structure of the State-Trait Anger Expression Inventory- 2 (STAXI-2) in a sample of 128 adult male forensic inpatients in the UK, as a reduction in the experience and expression of anger is a frequently targeted outcome for this group. Scale reliability indices and convergent validity were also investigated. Confirmatory factor analysis of the study sample responses suggested a poor fit with the six factors reported in the STAXI-2 validation study . Reliability indices (average variance estimation, composite reliability, alpha) of the STAXI-2 scales indicated “acceptable” internal consistency, specifically for State and Trait Anger and Anger Expression-In scales. Scale coherence was further supported by associations with theoretically related self-report and observer rated anger assessments. The findings offer support for the use of the STAXI-2 with people in forensic mental health services, but research into whether revisions to the assessment might improve its construct validity with this population is recommended. Based on this study samples reported levels of anger and normative comparisons, impression management considerations are advised when administering the STAXI-2.