Categorical data, where the observations of a variable are classified into one of a number of mutually-exclusive groups, is classified into two measurement scales for analysis:
By default Analyse-it assumes all variables are measured on a continuous scale, so for nominal and ordinal variables the measurement scale must be set (see Setting measurement scale for a variable).
Observations for nominal and ordinal scale data can be entered as group names, e.g. Male & Female, or as numeric codes, e.g. 1 & 2. Numeric codes are often used for brevity and quick data entry, but their meaning can be difficult to interpret and remember. To aid comprehension codes can be mapped to group names (see Mapping group names to codes).