intervalscale

The interval scale is a level of measurement in statistics that possesses the properties of nominal and ordinal scales, plus the characteristic that the differences between values are meaningful and equal. On an interval scale, data can be ordered, and the distance between any two successive points is the same. However, there is no true zero point; a zero on an interval scale does not signify the absence of the quantity being measured.

Examples of interval scale data include temperature in Celsius or Fahrenheit, and calendar years. While we can say that 20 degrees Celsius is 10 degrees warmer than 10 degrees Celsius, we cannot say that 20 degrees Celsius is twice as hot as 10 degrees Celsius because the zero point is arbitrary. Similarly, for Fahrenheit, 0 degrees does not mean there is no heat. Arithmetic operations like addition and subtraction are meaningful with interval data, but multiplication and division are not, due to the lack of a true zero. Statistical analyses suitable for interval data include calculating means, medians, standard deviations, and conducting t-tests and ANOVA.