Regression analysis is a statistical process for estimating the relationships between two or more variables. The relationship is modeled as $$y \sim x$$ or $$y = f(x)$$. Both model descriptions indicate that the variable $$y$$ is a function of $$x$$. Therefore the variable $$y$$ is denoted as response variable or dependent variable, whereas the variable $$x$$ is denoted as predictor variable or independent variable.