Residual sum of squares

In statistics, the residual sum of squares (RSS) is the sum of squares of residuals.

In a standard regression model $$y_i = a+bx_i+\varepsilon_i\,$$, where a and b are coefficients, y and x are the regressand and the regressor, respectively, and &epsilon; is the error term. The sum of squares of residuals is the sum of squares of estimates of &epsilon;i.

In general: total sum of squares = explained sum of squares + residual sum of squares.