What is a Discrete Random Variable?
Discrete Random Variable
A variable whose value is determined by the outcome of a random experiment, and which can only take a countable set of specific, separate values — typically whole numbers.
Think of a discrete random variable as a quantity that jumps between distinct values rather than flowing continuously. You can list all its possible outcomes.
Examples of discrete random variables:
- The number shown when rolling a fair six-sided die:
- The number of heads in 5 coin flips:
- The number of goals scored in a football match:
Contrast with continuous random variables (not covered here): those can take any value in a range, like height or temperature.
Exam Tip
A quick test: Can you list all the possible values? If yes, it's discrete. If the variable can take any value within an interval (like 1.732... or π), it's continuous.
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