The Longitudinal‐Experimental Design and the Development and Prevention of Criminal Offending Over the Life‐Course: Advances in Science and Policy From the Cambridge‐Somerville Youth Study.

Background: David Farrington (1944–2024) wrote extensively about the methodological rigour and utility of the longitudinal‐experimental research design to advance knowledge about the development, explanation, prevention and treatment of antisocial behaviour and criminal offending over the life‐course. Founded in 1935, the Cambridge‐Somerville Youth Study (CSYS) is recognised as the first randomised controlled trial in criminology and the first longitudinal‐experimental study in criminology. Aims: To report on key scientific and policy contributions made by the CSYS in investigating the development and prevention of delinquency and criminal offending over the life‐course. Methods: Uses previously analysed observational and experimental data from follow‐ups of study participants conducted in middle age (N = 494; mean = 47 years) and old age (N = 488; 84–92 years). Results: Identified several parental socialisation practices and interactions during childhood (but not father absence) as strongly associated with serious criminal offending in middle age. Support for peer deviancy as a causal mechanism for iatrogenic effects among treatment groups, compared to pair‐matched controls, during middle age drew policy attention to group‐based prevention interventions. Conclusions: The longitudinal‐experimental design is a highly important yet under‐utilised methodological approach in criminology. Future research should include revisiting the original plan for the design, addressing a key potential concern of the design and carrying out longer follow‐ups at key stages of the life‐course. [ABSTRACT FROM AUTHOR]