| Noun | 1. | curvilinear regression - the relation between variables when the regression equation is nonlinear (quadratic or higher order) statistics - a branch of applied mathematics concerned with the collection and interpretation of quantitative data and the use of probability theory to estimate population parameters regression toward the mean, simple regression, statistical regression, regression - the relation between selected values of x and observed values of y (from which the most probable value of y can be predicted for any value of x) |