What you'll learn
How to show and interpret the relationship between two variables.
Correlation
- Positive correlation: as one variable increases, so does the other.
- Negative correlation: as one increases, the other decreases.
- No correlation: no clear relationship. Correlation can be strong or weak.
Line of best fit
- Drawn through the data to model the trend, passing close to as many points as possible (often through the mean point).
- Interpolation (estimating within the data) is reliable; extrapolation (beyond the data) is not.
Correlation vs causation
- Correlation does not prove that one variable causes the other.
Exam tips
- Describe correlation using strength and direction.
- Use the line of best fit to make and justify estimates.
Common mistakes
- Claiming causation from correlation.
- Extrapolating far beyond the plotted data.