1970/02/01 by Arthur E. Hoerl, Robert W. Kennard · 9,132 citations
Engineering · Mathematics · #Advanced Statistical Methods and Models #Algorithm #Applied mathematics #Control Systems and Identification #Diagonal #Geology #Geometry #Least-squares function approximation #Mathematics #Regression #Residual #Ridge #Statistical and numerical algorithms #Statistics
paper · doi:10.1080/00401706.1970.10488634
published in Technometrics 12(1), 55-67 (Taylor & Francis)
openalex publication_date 1970/02/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
In multiple regression it is shown that parameter estimates based on minimum residual sum of squares have a high probability of being unsatisfactory, if not incorrect, if the prediction vectors are not orthogonal. Proposed is an estimation procedure based on adding small positive quantities to the diagonal of X′X. Introduced is the ridge trace, a method for showing in two dimensions the effects of nonorthogonality. It is then shown how to augment X′X to obtain biased estimates with smaller mean square error.