Recoding Categorical Variables

Recoding is the process of converting values from one coding scheme to another. It is common in clinical data preparation. A REDCap export may store sex as `1`, `2`, and `3`, while a report may need `Female`, `Male`, and `Not reported`. A checkbox field may export multiple binary variables that need to be summarized. A free text field may need classification into controlled categories after review. Recoding should always preserve a clear connection to the original value.