Final Results of a Matched-Pairs Reanalysis of Offending at Age 45

• In Event: New Findings from the Cambridge-Somerville Youth Study

Abstract

The Cambridge-Somerville Youth Study was last followed-up by Joan McCord, when participants were in their mid- to late forties (mean age = 45 years). McCord eventually located records for 494 (N=248 treatment, 246 control) of the 506 participants, and interviewed (or distributed questionnaires to) 347 of them. The follow-up revealed iatrogenic effects of the program: compared to the control group, significantly more members of the treatment group committed two or more crimes. While the CSYS used a matched randomized controlled experimental design, McCord’s follow-up did not remove both members of a matched pair if one member could not be located. The downside to removing both members of a matched pair is the potential loss of a substantial portion of the original sample, but this is far outweighed by the ability to overcome differential attrition, one of the advantages of the research design. This paper discusses the reanalysis of the age-45 evaluation of the CSYS with respect to offending. Particular focus is on heterogeneity in results based on different measures of offending (e.g., types, frequency, seriousness).

Authors

• Gregory M. Zimmerman, Northeastern University

• Brandon C. Welsh, Northeastern University / NSCR

• Steven N. Zane, Northeastern University