Partial regression
= Partial regression
{title2=$\widehat\beta_j=\frac{X_j^T(I-P_{-j})Y}{X_j^T(I-P_{-j})X_j}$}
Partial regression first projects a response and a selected predictor orthogonally off the remaining design columns. Regressing the residualized response on the residualized predictor yields its coefficient in the full <ordinary least squares> fit.