Sample size in prognostic factor research

The STROBE provides some explanations for this issue. Also, don’t calculate the sample size after data collection.

PubMed

Strengthening the Reporting of Observational Studies in Epidemiology...

Much medical research is observational. The reporting of observational studies is often of insufficient quality. Poor reporting hampers the assessment of the strengths and weaknesses of a study and the generalizability of its results. Taking into...

10 Study size: Explain how the study size was arrived at.