Life events were dated with a calendar, depression was checked through diagnostic interview and informant report, and genotype came from biological material. Depression rose as stressful events accumulated.
Compare Caspi's measures with the stress-exposure finding.
40 exam-style questions on Edexcel GCSE Psychology 3.2 Studies, covering 3.2.1 Caspi et al. (2003) and 3.2.2 Young (2007). Each one has a worked solution and a mark scheme showing where the marks go.