Question

Which of the following variables is an example of interval- ratio level of measurment?

a) social class

b) gender

c) political party

d) income

Answer 1

The answer to this is "d" Income.
This is because we can measure the distance or intervals between incomes like 5 dollars and 10 dollars, 2 pounds and 4 pounds. But we cannot do the same for social class, political party, and gender. These comes under ordinal and nominal scales of measurements for these can only be denoted by names, for example, gender (either male or female), social class (either upper class, middle class, lower class and so on).

I have described different scales below in case of any confusion related to scales of measurement.

There are 4 level of measurements:

• Nominal - This scale is used to denote something with the help of numbers or alphabets but does not have any real meaning. For example, Jersey number 1 denotes a particular player but does not mean that, that player is No.1.
• Ordinal - This is used when we can place something in order and this time, the ranks have real meaning to it. Common example is ranks of classmates based on academic scores. Here the ranks of students can tell you the order of their performance with respect to each other but cannot tell you the difference between the two.
• Interval - Now interval scale does that job which was not fulfilled by the ordinal scale. It can tell you the equal interval distance between two numbers. For example time, temperature, test scores. It does not have an arbitrary zero (i.e., presence of zero does indicate that it has real value). For example, 0 degree temperature does not indicate the absence of temperature, i.e., it has some value.
• Ratio - Ratio scale have all the properties of the above three scales and also have an arbitrary zero (i.e., presence of zero does indicate that it has real value) that was not present in any of the above three. For example, weighs. 0 gm would indicate absence of any weight.