While the Dunedin study is correlational (precluding definitive causal statements), there are several features of the study that help strengthen casual inference. These include: (a) a low attrition rate which enhances the accuracy of our effect size estimates; (b) use of multiple data sources—self-reports, tests, observations, records, informant reports (i.e., STORI), which permits replication checks across sources, and allows for construction of multiple-indicator measurement models; (c) our long history of proven confidentiality and non-intervention enhances frank reports on delicate topics; and (d) face-to-face interviewing conducted at the Unit insures privacy which avoids falsification, reduces nay-saying to hasten the assessment process, and facilitates breadth of data collection (e.g. biological data can be collected under controlled conditions, using state-of-the-art technology).
