Interval Scale Of Measurement

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.

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Ordinal Scale Of Measurement

Ordinal scale has natural or intrinsic order in its different items or values. For example when dealing with various education levels we say primary, middle, secondary, under graduate and post graduate education. Here order exists among various levels of education.  And we know that a person with primary level of education is less educated than a person with middle level of education and so on. Similarly when dealing with teaching profession we say elementary school teacher, secondary school teacher, higher secondary school teacher, lecturer, assistant professor, associate professor and professor etc. Here we know that elementary school teacher is lower in rank than secondary school teacher and secondary school teacher is lower in rank than lecture or professor. Similarly you can think of various ranks of military personnel like lieutenant, captain, major and lieutenant colonel etc. Various stages of human life like infancy, childhood, adolescence, adulthood, and old age is another example of ordinal scale. Likert scale, Bogardus Social Distance Scale, Tharstone Scale and Semantic Differential Scale are some additional examples of nominal scale. In ordinal scale, though we know that there is a difference among its various items or values but we can't say how much is it. Nominal and Ordinal scales are sometimes called nonparametric scales which means that parametric statistics can’t be used with them. The other three types of scales are: nominal, interval and ratio.

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