Outlier
A value far from the rest of its column. It may be an error, or it may be the most interesting row in the file.
Outliers should be investigated before they are removed. Deleting them because they are inconvenient is how real events disappear from data.
Where it comes up
- Mixed unitsValues in one column are measured in different units, sometimes with the unit written in the cell and sometimes not.
See also
- Data profilingExamining a dataset to describe what is actually in it: types, ranges, distinct values, blanks, and patterns, column by column.
- 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.