Long-term follow-ups of experimental interventions

Abstract

The book Understanding and Controlling Crime: Toward a New Research Strategy (Farrington et al. 1986) set out in great detail the advantages of a project in which there were several years of data collection (preferably in face-to-face interviews), followed by one experimental intervention, followed by several more years of data collection. However, as shown in the more recent reviews by Farrington (2006), Loeber and Farrington (2008), and Farrington et al. (2010), these kinds of longitudinalexperimental studies have never been carried out in criminology. There have been a number of longitudinal-experimental studies in which an initial experimental intervention was then followed up over time. However, very few of these projects have involved really long-term follow-ups. Farrington and Welsh (2013) reviewed randomized experiments with at least 50 persons per condition initially, or at least 100 persons initially allocated to two conditions: an outcome measure of offending, and a follow-up period after the intervention of at least 10 years, with interview, questionnaire, or record data. They found that only 12 longitudinal-experimental studies of this nature had ever been completed up to 2011. The longest-lasting projects were the CambridgeSomerville Study (38 years; McCord 1990) and the Perry Preschool Program (36 years; Schweinhart et al. 2005). Other long-lasting studies with follow-up interviews or questionnaires were the Abecedarian project (21 years; Campbell et al. 2002), the Nurse-Family Partnership (19 years; Eckenrode et al. 2010), the Infant Health and Development Program (18 years; McCormick et al. 2006), and the Montreal Longitudinal-Experimental Study (17 years; Boisjoli et al. 2007). These were the most important six studies; other projects had shorter follow-ups (e.g., Fast Track: CPPRG 2010), had follow-ups only in records (e.g., the Missouri Delinquency J Exp Criminol (2013) 9:385–388 DOI 10.1007/s11292-013-9195-y