Categorical data
Values that place each row in one of a limited set of groups, such as a status of open, pending, or closed. The values are labels, not quantities.
A category stored as a number, such as region 1 to 5, is still a label. Averaging it produces a figure that means nothing.
Where it comes up
- Inconsistent category labelsA column meant to hold a few fixed values holds many spellings of them.
- Categories that changed meaningA label stays the same across the file, but what it covers was redefined partway through.
- Codes without a lookupA column holds short codes such as 3, A, or XR, and the table that says what each code means is not in the file.
See also
- Controlled vocabularyA fixed, agreed list of the values a field is allowed to hold, such as the two-letter codes for US states.
- CardinalityThe number of distinct values in a column. A country column has low cardinality; an email column has high cardinality.
- Canonical valueThe one agreed spelling for a thing that can be written several ways, such as VA for Virginia, virginia, and Va.