Ceteris LabInteractive Econometrics

Lesson 7

Probability basics

Big question

How do we talk about uncertainty in a disciplined way?

Lesson progress

Complete checkpoints as you learn

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Learning objectives

  • Explain probability basics in plain language.
  • Use event correctly in an interpretation.
  • Connect the lesson idea to a formula, graph, Python result, or real example.

Simple explanation

Probability gives numbers to uncertainty. It helps us describe events, compare risks, and understand why samples can differ from the full population.

Key terms

Event
An outcome or set of outcomes we care about.
Probability
A number from 0 to 1 that describes how likely an event is.
Complement
The event that something does not happen.
Independence
Two events are independent if one happening does not change the probability of the other.

Complement rule

P(not A)=1P(A)P(\text{not A}) = 1 - P(A)

Example

If the probability of being employed is 0.92, the probability of not being employed is 1 - 0.92 = 0.08.

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 does a probability of 0 mean?

Key takeaway

Probability is the language econometrics uses to handle uncertainty.