Topic summary
Interval Scale
Extracted from the Wikipedia article Level of measurement.
Interval scale
The interval type allows for defining the degree of difference between measurements, but not the ratio between measurements. Examples include temperature scales with the Celsius scale, date when measured from an arbitrary epoch (such as AD), location in Cartesian coordinates, and direction measured in degrees from true or magnetic north. Ratios are not meaningful since 20 °C cannot be said to be "twice as hot" as 10 °C, nor can multiplication/division be carried out between any two dates directly. However, ratios of differences can be expressed; for example, one difference can be twice another; for example, the ten-degree difference between 15 °C and 25 °C is twice the five-degree difference between 17 °C and 22 °C.