Correlation coefficient may refer to:
- Pearson product-moment correlation coefficient, also known as r, R, or Pearson's r, a measure of the strength and direction of the linear relationship between two variables that is defined in terms of the (sample) covariance of the variables divided by their (sample) standard deviations
- Correlation and dependence, a broad class of statistical relationships between two or more random variables or observed data values
- Goodness of fit, which refers to any of several measures that measure how well a statistical model fits observations by summarizing the discrepancy between observed values and the values expected under the model in question
- Coefficient of determination, a measure of the proportion of variability in a data set that is accounted for by a statistical model; often called R2; equal in a single-variable linear regression to the square of Pearson's product-moment correlation coefficient. (The strength of the linear relationship between the values)
- Intraclass correlation, a descriptive statistic that can be used when quantitative measurements are made on units that are organized into groups; describes how strongly units in the same group resemble each other.
- Rank correlation, the study of relationships between different rankings on the same set of items