Examining the Construct Validity of the Original and Revised JBS: A Cross-Validation of Sample and Method

Factor analysis is a statistical technique that can provide an understanding of construct validity. Previous research examining the factor structure of the Juror Bias Scale (JBS) has uncovered problems in the scale's assessment of the constructs of probability of commission (PC) and reasonable doubt (RD). We here reevaluate the scale's constructs to better our understanding of the pretrial biases involved in the juror decision-making process. Importantly, previous findings have been limited to college student samples and trial material that has involved rape evidence. This study examines the construct validity of the JBS in a sample of 617 jury-eligible adults drawn from the community, and the predictive validity of the JBS is examined across 3 distinct trial scenarios. The results parallel earlier findings, indicating that although RD is a tenable and useful construct affecting juror decision-making, PC may be a less relevant pretrial bias. We therefore suggest that future research emphasize alternative constructs, such as confidence and cynicism in the criminal justice system.     

Revising the Factor Structure of the Juror Bias Scale: A Method for the Empirical Validation of Theoretical Constructs

The application of factor analytic techniques to explore the construct and predictive validity of a popular scale used for the identification of pretrial juror bias is herein reported. A confirmatory factor analysis (CFA) was employed on the Juror Bias Scale (JBS) scores of 301 participants, but empirical findings did not support the theoretically derived single-factor scales of Probability of Commission and Reasonable Doubt. Empirically driven alternative models were generated using exploratory factor analysis. The JBS scores of an additional 301 participants were then employed to cross-validate the initial findings using nested modeling CFA. The empirical model achieved a significantly improved fit over the theoretical model and resulted in the elimination of approximately 30% of the original items with no attenuation in the scale's ability to predict juror verdicts. Moreover, a theoretical reorganization of the items was consistent with the empirically derived model and provided a rationale for altering the scoring of the JBS which, in turn, maximized its predictive validity. The use of CFA techniques to aid in the development of scales assessing jury attitudes and biases is discussed.