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Data & Analytics · Intermediate

Correlation Coefficient

Pearson's r: a value from -1 to +1 measuring the strength and direction of a linear relationship between two numeric variables.

Definition

r near ±1 means a strong linear relationship, and r near 0 means no linear relationship (though a nonlinear one may exist). r is sensitive to outliers. R² in simple linear regression equals r².

Exam tip

r = 0 means no linear relationship, not no relationship at all; plot the data.

Related terms