Correlation

Math

Definition

Correlation measures the strength and direction of the linear relationship between two quantitative variables. The correlation coefficient r ranges from -1 to 1, where values near ±1 indicate strong linear relationships and values near 0 indicate weak or no linear relationship.

Examples

  • Height and weight typically have a positive correlation (r ≈ 0.7)
  • Hours of TV watched and GPA might have a negative correlation
  • Shoe size and intelligence have roughly zero correlation
Key Fact

r ranges from -1 to 1; r² gives the proportion of variance explained.

Related Terms

Scatter plots Least-squares regression Line of best fit

Study This Concept

Practice correlation with free review games in these units:

AP Statistics Unit 2: Exploring Two-Variable Data