An interval measure is one where the distance between the attributes, or response options, has an actual meaning and is of an equal interval. Differences in the values represent differences in the attribute. For example, the difference between 3 and 4 is the same as the difference between 234 and 235. Interval measures have fixed measurement units, but they do not have a fixed, or absolute, zero point. Because of this, it is technically not correct to declare that something is so many times larger or smaller than something else, although this often is done nonetheless.

Unlike other less sophisticated levels of measurement (e.g. nominal and ordinal measures), interval measures have real meaning. The relationship between the value and attribute is meaningful. For instance, temperature (Fahrenheit ...