 Frisch–Waugh–Lovell theorem

The Frisch–Waugh–Lovell theorem says that a regression coefficient can be obtained by residualizing both the response and its predictor against the remaining predictors and then regressing one residual on the other.

The Frisch-Waugh-Lovell (FWL) theorem is an important result in econometrics that deals with the properties of linear regression models. It provides a method to interpret the results of regression analyses, particularly when some of the independent variables are of primary interest while others are controlled for.