Levels of Measurement

Also known as scales of measurement, levels of measurement describe how data variables, numbers, and associated attributes are defined and categorized. Mathematical operations and statistical techniques have requirements that must be met in order for meaningful data analysis and interpretation to be undertaken. An assessment of the data measurement level facilitates determining the appropriate statistical analysis to use based on the data parameters. Listed in order of increasing variable complexity, four major levels of measurement are commonly identified: nominal, ordinal, interval, and ratio. This entry describes each of these levels.

Nominal level is the lowest or simplest measurement level. Information is assigned to categories that are mutually exclusive (a single group) and all-inclusive (contain all cases). The categories do not have any meaningful ordering and only ...