Définition Categorical

Unlike metric data, categorical data do not consist of interval-scaled numerical values, which would allow for arithmetic calculations. Categorical variables occur in nominal and ordinal scales, such as the answers to questions about sex, residence, or level of personal satisfaction. Although the variables 'male' and 'female' can be represented by the numerical values 1 and 2, the value 2 does not represent twice as much as the value 1.

The same applies to a rating scale which states personal satisfaction levels with the numbers 1-7. The answer 6 does mean that the respondent is 50% more satisfied than a respondent who answered 4.