a scale marked in equal intervals so that the difference between any two consecutive values on the scale is equivalent regardless of the two values selected. Interval scales lack a true, meaningful zero point, which is what distinguishes them from ratio scales. For example, Fahrenheit temperature uses an interval scale: The difference between 50 °F and 49 °F is the same as the difference between 40 °F and 39 °F, but a temperature of 0 °F does not indicate that there is no temperature. See also interval data.