Schema
The declared structure of a dataset: its columns, their names and types, and the rules they must satisfy.
A spreadsheet has no enforced schema, which is why anything can end up in any cell. Much of data cleaning is recovering the schema the data was supposed to follow.
Where it comes up
- Multiple values in one cellA single cell holds a list, or two different facts, joined by a comma, slash, or line break.
See also
- Data typeThe kind of value a column holds, such as text, whole number, decimal, date, or true and false. The type decides what operations make sense.
- ValidationChecking values against rules, such as a date being in the past or a state code being on the allowed list, and reporting what fails.
- Tidy dataA table layout in which each row is one observation, each column is one variable, and each cell holds one value.