Farrington et al (2006) - cambridge study in delinquent development

Strengths:

- large sample (411) considered reliable.

-longitudinal: allows for development of behaviour over time to be identified. more reliable than snapshot.

-useful: concludes most prolific offenders start early, suggests to target resourses ten-year-olds (eg, emphasis on education etc)

weaknesses:

- self-reports: liable to socially desirable responses/ lying: reduces validity

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