A Meta-Analysis on Joinder Effects: Do They All Have the Same Magnitude?

Author

• Amelia M. Tisk, CUNY John Jay CollegeFollow

Date of Award

Spring 5-2026

Document Type

Thesis

Degree Name

Master of Arts (MA)

Department/Program

Forensic Psychology

Language

English

First Advisor or Mentor

Steven Penrod

Second Reader

Dilhan Toredi

Third Advisor

Mark Fondacaro

Abstract

The present meta-analysis examined whether different forms of joinder and procedural consolidation produce varying levels of prejudice in adjudicative decision-making. Although joinder procedures improve judicial efficiency, psychological research has suggested that combining charges, defendants, or plaintiffs within a single proceeding may increase conviction likelihood, liability judgments, and broader perceptions of wrongdoing. A random-effects meta-analysis was conducted across 22 independent study effects examining charge joinder, defendant consolidation, plaintiff consolidation, multiple-complainant procedures, and related aggregation paradigms. Effect sizes were converted to Pearson’s r whenever possible. Overall, procedural aggregation produced a moderate effect on adjudicative outcomes, r = .27, 95% CI [.22, .32]. Subgroup analyses indicated that charge-joinder and plaintiff-consolidation paradigms produced the strongest and most consistent prejudice effects, whereas defendant-consolidation and multiple-complainant paradigms produced weaker and more context-dependent findings. Heterogeneity analyses suggested meaningful variability across legal contexts and procedural conditions. Overall, the findings indicate that joinder-related prejudice is not uniform across paradigms and appears strongly influenced by evidentiary structure, deliberation conditions, and contextual factors.

Recommended Citation

Tisk, Amelia M., "A Meta-Analysis on Joinder Effects: Do They All Have the Same Magnitude?" (2026). CUNY Academic Works.
https://academicworks.cuny.edu/jj_etds/392