# Understanding probability & the relationship with inference

## Learning outcomes

On watching this video, students should be able to:

- Explain the frequentist definition of probability
- Explain how probability is used in statistical inference
- Explain the concept of independence and appreciate why it is an important concept in statistical inference.
- Identify and calculate marginal, joint and conditional probabilities in a contingency table.
- Understand that when two events are not independent, we cannot calculate their probability by simply multiplying each of their marginal probabilities.
- Understand how easy it is to flip the interpretation of a conditional probability and draw wrong conclusions.
- Use contingency tables and probability trees to help understand probabilities.

Correction

05:10: The slide says “P(G,G,B)”, this is not quite the correct notation because this would normally be read as the probability of having 2 girls and a boy, but the point about multiplying independent events to work out the probability of a sequence is true.