Interval scale has both order and measurable interval. In other words all the values on this scale have proper order i.e. they can be put in ascending or descending order, and the interval between any two values on this scale can be measured. Unlike Nominal and Ordinal scales, all the values on interval scale have numerical meaning and they can be easily subtracted or added. But multiplication and division have no sense for this scale. Temperature is a simple example of interval scale. We can subtract or add different values of temperature for example: 3 degrees + 2 degrees = 5 degrees and 5 degrees – 2 degrees= 3 degrees. But if we multiply 20 degrees by 2 degrees which will give us 40 degrees it will make no sense, as 40 degrees will not definitely mean two times more heat as compared to 20 degrees. Similarly dividing 20 degree by 2 will give us 10 degrees, but again, it does not mean that 10 degree will give us half of 20 degrees temperature. Interval scale of measurement has no absolute zero which means that it can assume values both below and above zero. In our example of temperature, zero doesn’t mean no temperature but it represents just one value on this scale. We know that temperature can goes beyond zero and it can assume even negative values. That is why in winter we sometimes have minus 1, 2, and 3 … degrees of temperature. You might also interested in knowing about the other three types of measurement scales: nominal, ordinal and ratio.
