CORRELATION COEFFICIENT
Back to GlossaryDefinition
A statistic, typically denoted r, that quantifies the strength and direction of a linear relationship between two variables.
Summary
A correlation coefficient is a numerical value between -1 and 1 that tells you how closely two variables move together in a straight-line relationship. Think of it as a measure of how predictable one variable is based on another. A value of +1 means perfect positive correlation (as one goes up, the other always goes up proportionally), -1 means perfect negative correlation (as one goes up, the other always goes down proportionally), and 0 means no linear relationship exists between the variables.
Usage Context
Essential for understanding data relationships in research methods, interpreting statistical studies, hypothesis testing, and as a foundation for regression analysis and predictive modeling.
Common Confusions
- Thinking correlation implies causation
- Believing that correlation can detect non-linear relationships
- Assuming that r = 0 means no relationship exists (could be non-linear)
- Confusing correlation coefficient with coefficient of determination (r²)
- Not understanding that correlation is sensitive to outliers
