Nominal Scale

A nominal scale is a scale of measurement used to assign events or objects into discrete categories. This form of scale does not require the use of numeric values or categories ranked by class, but simply unique identifiers to label each distinct category. Often regarded as the most basic form of measurement, nominal scales are used to categorize and analyze data in many disciplines. Historically identified through the work of psychophysicist Stanley Stevens, use of this scale has shaped research design and continues to impact on current research practice. This entry presents key concepts, Stevens's hierarchy of measurement scales, and an example demonstrating the properties of the nominal scale.