Analytic Plan
Whereas Peterson et al. (10) and Baskin and Sommers (12,13) analyzed the effect of forensic evidence on case-processing outcomes within specific offense categories and within specific sites, we instead analyzed the data in aggregate form while controlling
for offense seriousness and study site.
We believe combining these data reflect a more generalized, systems perspective
that investigates the role of forensic evidence (of any type) on case-processing outcomes.
Similar to Peterson et al. (4), our variable indicating offense seriousness ranged from 1 (low) to 5(high), with values determined by the offense type (5 = homicide,
4 = rape, 3 = assault, 2 = robbery, 1 = burglary).
However,given prior research demonstrating a nonlinear effect of offense seriousness (4), we chose to model this variable as a categorical indicator, with the assumption of ordinal properties.
The analysis proceeded in three stages, beginning with basic descriptive statistics, moving to a bivariate analysis of forensic evidence variables, and case-processing outcomes and finally to multivariate models predicting each outcome.