r (Pearson Correlation Coefficient)

Random Effects (in Mixed Model ANOVA)

Random Numbers from Arbitrary Distributions

Random Sub-Sampling in Data Mining

Receiver Operating Characteristic Curve (ROC Curve)

Regularization in Neural Networks

Rejection Region/Acceptance Region

Relative Function Change Criterion

Replication (in Experimental Designs)

Robust Locally Weighted Regression (LOWESS)

Root Mean Square Standardized Effect (RMSSE)