| ||Literature Coverage Dates||Number of Studies||Number of Study Participants|
|Meta-Analysis 1||1993 - 2005||7||0|
|Meta-Analysis 2||1998 - 2010||34||6868|
|Meta-Analysis 3||1994 - 2006||21||0|
|Meta-Analysis 4||1996 - 2006||15||0|
Latimer, Morton-Bourgon, and Chrétien (2006) located seven individual studies occurring between 1993 and 2005 to determine if drug treatment courts for youth reduce recidivism compared to traditional juvenile justice system responses. To be included in the analysis, studies needed to have (1) examined the effectiveness of a juvenile drug court, (2) used a control group that did not experience the juvenile drug court, (3) included sufficient statistical information to establish an effect size, and (4) measured the impact of the juvenile drug court on recidivism rates. Age, length of the program, follow up period, and methodological versus random assignment were identified as moderating variables in the analysis.
The search resulted in the inclusion of seven studies of seven individual drug court programs. The studies included published and unpublished evaluations. The individual program studies included youth offenders who had successfully completed a drug treatment court program. No information was provided on the gender, racial/ethnic breakdown of the studies’ samples, or program location.
The phi coefficient (Pearson’s r product moment correlation applied to dichotomous data) was used as the effect size estimate. Once the effect size estimate from each program was calculated for recidivism, the overall mean effect size estimate, along with the corresponding confidence intervals, and a weight effect size estimate were calculated.Meta-Analysis 2
Mitchell and colleagues (2012) conducted an extensive search process for studies that (1) evaluated a drug court program (defined as specialized courts for handling drug-involved cases that are processed in a non-adversarial manner, refer offenders to appropriate treatment programs, regularly test offenders for drug use, and have a judge who actively monitors progress and provides sanctions for misbehavior), (2) included a comparison group in the evaluation that was treated in a traditional fashion by the court system, (3) measured criminal behavior (such as arrest or conviction), and (4) provided enough information to compute an effect size.
The search process resulted in the inclusion of 154 independent evaluations of drug courts. Of those, 34 examined juvenile drug courts. Only 9 percent of the studies were published (as journal or book chapters), while the other 91 percent were unpublished reports. The 34 studies included 6,868 study participants. Almost all of the juvenile drug court evaluations had study participants that were predominantly male. Ninety-four percent of the juvenile drug court studies included mostly males (60-90 percent) and 5 percent included only males. A little over half (53 percent) of the studies included only non-violent offenders, while 12 percent included violent offenders (the other 35 percent of the studies did not report the offender type). Nearly half (47 percent) of the studies evaluated juvenile drug court programs that included a four-phase process.
For each evaluation contrast, an effect size was calculated. Effect sizes were calculated for three outcomes: (1) general recidivism; (2) drug related recidivism; and (3) drug use. The authors utilized the odds ratio effect size, as this type of effect size is most appropriate for dichotomous recidivism. The inverse variance weight was calculated for each program effect and those weights were used to compute the average. A random effects model was used for the analysis.
In order to assess the robustness of the findings against the methodological quality of the studies included in the meta-analysis, the 154 studies were placed into four possible categories: (1) weak quasi-experiments, (2) standard quasi-experiments, (3) rigorous quasi-experiments, and (4) randomized experiments.Meta-Analysis 3
Shaffer (2006) sought to identify characteristics of effective juvenile drug courts. The author used meta-analytic techniques to investigate the relationship between six structural and five process dimensions of juvenile drug court effectiveness. The six structural dimensions included (1) target population, (2) leverage, (3) service delivery, (4) staff, (5) funding, and (6) quality assurance. The five process dimensions included (1) assessment, (2) philosophy, (3) treatment, (4) predictability, and (5) intensity. The objective was to merge survey data with existing study data to determine the relative influence of each dimension listed above.
Multiple sources were searched to locate both published and unpublished studies related to drug court effectiveness through January 2006. The inclusion criteria required that studies (1) evaluated a drug court program using an experimental or quasi-experimental design, (2) included a distinct comparison group, (3) used at least one measure of criminal behavior as an outcome measure, (4) had a minimum 6-month follow-up period, and (5) were based in the USA. Applying these criteria resulted in 115 eligible studies. However, in several cases, multiple publications reported on the same drug court.
The search procedures resulted in the identification of 21 unique studies reporting on 21 distinct drug courts. Most of the studies collected were technical reports (68.3 percent) with just over 25 percent published in scholarly journals or as book chapters. No information was provided on the age, gender, or racial/ethnic breakdown of the studies’ samples, or on the program location.
The effect size was calculated for each program using the phi coefficient. The phi coefficient was selected because of its equivalence to the Pearson’s product–moment correlation coefficient, ease of interpretation, and ability to be converted into the binomial effect size display. After calculating the effect size for each program, a weighted mean Pearson coefficient was estimated to assess the mean effect size associated with drug courts. The inverse variance weight was calculated for each program effect and those weights were used to compute the average. The fixed effects model was used for the analysis.Meta-Analysis 4
Drake (2012) conducted a meta-analysis to review the effectiveness of various types of chemical dependency treatment in the adult and juvenile justice systems to determine whether the programs reduce crime and substance abuse. For evaluation of juvenile drug court studies, four primary methods were used to locate studies: (1) bibliographies of systematic and narrative reviews in various topic areas were consulted; (2) citations from the individual studies were examined; (3) independent searches of research databases were conducted; and (4) authors of primary research were contacted. Studies were included if they had a comparison group (random or non-random assignment), had enough information to calculate an effect size, and had a standardized measure of the primary outcome of interest (i.e., crime).
The search process resulted in the inclusion of 15 evaluation studies of juvenile drug courts. The 15 individual studies represented 15 effect sizes (some studies reported on more than one program). No information was provided on the number or demographics of the participants, nor was information provided on the distribution of published and unpublished studies.
The standardized mean difference effect size was calculated for each program effect. Once the effect sizes were calculated, the individual measures were summed to produce a weight average effect size for the program area (in this instance, adult drug courts). Adjustments were made to the effect sizes for small sample sizes, evaluations of “non-real world” programs, and for the quality of the research design (the quality of each study was rated using the University of Maryland’s six-point scale; only studies that received a rating of ‘1’ or higher on the scale were included in the analysis). Random effects inverse variance weights were used to calculate the weighted average effect size.