Discrete Variables [ Definition & Examples ]

You can either classify numeric variables as discrete or continuous. Both these types of variables, discrete and continuous, are taught in introductory statistics classes. However, we will only be discussing discrete variables in detail in this piece. I will also put forward examples to strengthen your understanding since knowing just the definition wouldn’t be enough to clear the concept. 

Definition of Discrete Variables 

Note: The three properties of discrete variables listed below might not necessarily make the concept clear, but are required to understand the examples stated below.

A Discrete variable has the following three properties:

1. Discrete Variables have finite or countably infinite values.
2. Discrete variables are counted, not measured.
3. Discrete variables can only take specific values that cannot be divided. 

Examples of Discrete Variables

1. Money in your bank

The amount of money in your bank is a discrete variable because it is countable. Even if you tried counting the money in everyone’s bank, it would still be discrete since the sum of all money is countably finite.

Money in the bank also fulfills the second and third conditions; it is something that is counted, not measured; and it cannot be divided into decimal values like 5.365.

2. Age in Years

Age in years would be a discrete variable since it can be counted. For example, one can be 17 years old. 

However, if one were to try to calculate age with exact precision, it could take uncountably infinite values. For example, your present age could be 21 years, 10 months, 4 days, 4 hours, 19 seconds, 56 milliseconds, 34 nanoseconds, 64 picoseconds…..and so on. In that case, age would not be a discrete variable but a continuous variable. 

Discrete Variables Practice Examples With Answers

Now, to ensure you have understood the concept of discrete variables, try to think if the following would be discrete variables or not:

1. Country of Birth
2. Weight in Kilograms 
3. Precise Weight in decimals
4. Number of books on the shelf in the library

Answers:

1. Discrete variable
2. Discrete variable
3. Not a Discrete variable
4. Discrete variable

If you want to learn the difference between discrete and continuous variables, check out this article.