Guidance for designing and analysing observational studies: The strengthening analytical thinking for observational studies (STRATOS) initiative

Observational studies pose a number of biostatistical challenges. Methodological approaches have grown exponentially, but most are rarely applied in the real world. The STRengthening Analytical Thinking for Observational Studies (STRATOS) initiative is an international collaboration that was formed to provide guidance to help bridge the gap between methodological innovation and application. STRATOS is focused on identi-fying issues and promising approaches for planning and analysing observational studies. Crucially, STRATOS will communicate its findings to a wide audience with different levels of statistical knowledge. In this article, we provide an example illustrating the need for such guidance and describe the structure, general approach, and general outlook of the STRATOS initiative.