Lesson 8
Random variables
Big question
How can one variable have uncertain possible values?
Lesson progress
Complete checkpoints as you learn
Learning objectives
- Explain random variables in plain language.
- Use random variable correctly in an interpretation.
- Connect the lesson idea to a formula, graph, Python result, or real example.
Simple explanation
A random variable is a variable whose value is not known before observing it. In economics, wage, income, firm sales, and unemployment duration can be treated as random variables.
Key terms
- Random variable
- A variable with values determined by uncertain outcomes.
- Expected value
- The long-run average value of a random variable.
- Distribution
- A description of possible values and how likely they are.
- Realization
- The value we actually observe.
Expected value idea
Example
Before a graduate gets a job, their starting wage is uncertain. After the job offer, the wage is observed.
Checkpoint activity
Pause and explain this lesson's main idea in your own words before moving forward.
Try it yourself
Write one plain-English sentence explaining the main idea from this lesson.
Common mistakes
Check these before you move on.
A regression coefficient describes a pattern unless the assumptions or research design support a causal interpretation.
Quick quiz
What is a realization?
Key takeaway
Random variables help connect real-world uncertainty with data analysis.