Align the inputs
Compute returns and the risk-free rate on compatible periods. State whether the sample standard deviation is used and how missing observations are handled. Comparing a daily return series with an annual risk-free number directly is inconsistent.
Explain annualization
The familiar square-root-of-periods adjustment relies on assumptions about the return process. Serial correlation or non-uniform sampling can make a mechanical adjustment misleading. A ratio without its frequency and method is incomplete.
Read other measures too
A Sharpe ratio does not describe every aspect of tail risk or liquidity. Inspect drawdowns, exposure and the underlying return distribution. A zero-volatility sample also needs explicit handling rather than a silently infinite score.
Sources & references
References support specific definitions or methodological context. Examples and research checklists are explanatory; no performance result is claimed.