interval scale

A numerical scale where intervals between successive points on the scale are equivalent.

The classic interval scale is temperature: a difference of one degree means the same, whether it is between 0 and 1, or between 99 and 100. A one degree interval has the same meaning at every point on the temperature scale. This is in contrast to ordinal scales (such as position in a race), where the difference between 1 and 2 is not necessarily the same as the difference between 2 and 3, or other adjacent pairs. Interval scale is also different from a ratio scale.