The aboriginal birth cohort study: When is a cohort study not a cohort design?

Aims: The paper describes how a variety of different epidemiological study designs can be applied to data arising from a single prospective study. Methods: An overview of the data collection phases of the Aboriginal Birth Cohort Study is given. We illustrate how different research questions that require different analytical designs can be asked of the data collected in the present study. Results: With reference to five generic questions in health research, we showed how sixteen specific questions could be addressed in the Aboriginal Birth Cohort Study. These referred to a range of analytical designs. Conclusion: Readers need to take care not to confuse the overall design of a study with the design of a specific analysis. When conducting systematic literature reviews, studies should be classified according to the analytical design used in the specific report included in the review and not according to the design of the overall project.