Coding research participants into qualitative variables such as male and female represents

Coding participants into categories like male and female represents the nominal scale.

The nominal scale merely names or labels; its numbers only classify, not rank.

The Thurstone scale is an equal-appearing interval attitude scale, not mere labelling.

The Likert scale is a summated ordinal rating of agreement, not classification.

The differential scale ranks attitude positions and does not simply name categories.

The only permissible operation on nominal data is counting frequencies.