Ideally, causal research questions will be answered with randomized trials, but this is not always feasible for practical, ethical, or methodological reasons. To obtain a reliable answer to causal questions with observational data, target trial emulation has been introduced, in which an observational study is designed, conducted, and analyzed emulating the target trial. After phrasing a causal question, this framework first addresses seven components of the target trial protocol: eligibility criteria, treatment strategies, assignment procedures, follow-up period, outcome of interest, causal contrast of interest, and statistical analysis plan. Subsequently, these elements are emulated in the observational study. This approach addresses methodological pitfalls before initiating the study, draws more unambiguous conclusions, and provides a structured assessment of limitations of observational studies as well as randomized trials. The use of the target trial framework to support the design of observational studies is increasing.

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