A basic and important guideline for the selection of statistics is the level of measurement, which describes the mathematical characteristics of the variable. Determining at which one of three levels a variable has been measured is critical because the mathematical nature of the variable determines which statistics can be used.
In the table that follows, match each characteristic of a measure to the type of measure.
Description
Nominal Measures
Ordinal Measures
Interval-Ratio Measures
Variables measured at this level are classified into distinct categories that provide only the information that the scores are different from one another.



Variables measured at this level permit the broadest range of mathematical operations, including addition, subtraction, multiplication, and division.



Variables measured at this level allow judgments about “greater than” or “less than” but cannot be added, subtracted, multiplied, or divided.