Make the table consistent
A tidy table uses one row per record and one column per field. Keep one header row, avoid merged cells in the data area, and use a consistent format for dates and categories. This structure makes filters and summaries more reliable.
Check data quality
Look for blank required values, duplicate records, mixed spelling, and numbers stored as text. Keep a copy of the original data and document changes. Do not delete unusual values simply because they look surprising; first check whether they are valid.
Try it
Select a table and identify one consistency issue. Fix it in a copy, record the change, and compare the row count before and after.
Key takeaways
- Use one row per record and one column per field.
- Check duplicates, missing values, and inconsistent formats.
- Keep the source and document transformations.