Question

Level of measurement of a variable with examples

Answer 1

There are typically four levels of measurement that are defined:

1) Nominal , 2) Ordinal , 3 ) Interval , 4) Ratio

1) Nominal -

Nominal variables (also called categorical variables) can be placed into categories. They don’t have a numeric value and so cannot be added, subtracted, divided or multiplied. They also have no order.

Eg: Shoes can be categorized based on type (sports, casual, others) or color (black, brown, others).

2) Ordinal -

In the ordinal level of measurement, the variables are still classified into categories, but these categories are ordered and there is no equivalent distance between the categories

Eg: class variable for a person can have values like upper class, lower class, middle class etc.

3) Interval -

In the interval level of measurement, the variables are still classified into ordered categories, but there is an equivalent distance between these categories.

Eg: Shoe size. We can say that the difference between size 3 and size 4 shoe is equal to the distance between size 7 and size 8 shoe, but size 6 shoe is not equal to 2 * size 3 shoe. Also, size 0 shoe does not mean that there is no shoe, its simply a shoe with zero size i.e an arbitrary zero point.

4) Ratio -

The ratio level variables have all of the characteristics of nominal, ordinal and interval variables, but also have a meaningful zero point. So the zero point is real and not arbitrary, and a value of zero actually means there is nothing. So we can add, subtract, divide and multiply the two ratio level variables.

Eg: Weight of a person. It has a real zero point, i.e zero weight means that the person has no weight. Also, we can add, subtract, multiply and divide weights at the real scale for comparisons.