A META-ANALYTIC REVIEW OF COMPETENCY TO STAND TRIAL RESEARCH

The present study is a meta-analysis of competency to stand trial research. One meta-analysis was previously conducted in this area, but the large number of empirical studies that have been conducted since and the introduction of new instruments and revision of old instruments warranted updating and expanding upon the previously conducted study via contemporary meta-analytic methods. We meta-analyzed 68 studies published between 1967 and 2008 that compared competent and incompetent defendants on a number of demographic, psychiatric, and criminological variables. Categorical and continuous variables commonly investigated in competency research were coded and aggregated to generate cumulative effect sizes in the form of odds ratios and Cohen's d statistics, and moderation was tested via meta-F and meta-regression analyses. The most robust findings were that defendants diagnosed with a Psychotic Disorder were approximately eight times more likely to be found incompetent than defendants without a Psychotic Disorder diagnosis and the likelihood of being found incompetent was approximately double for unemployed defendants as compared to employed defendants. The likelihood of being found incompetent was also double for defendants with a previous psychiatric hospitalization compared to those without a hospitalization history. Comparative data on 12 competency assessment instruments and three traditional instruments were also explored and the effect sizes associated with the competency measures were substantially larger (i.e., approximately one Cohen's d-point) than those for the traditional measures. Limitations of the primary research and the previous and present meta-analyses are presented and future directions in this area are outlined.