Ill-conditioning and multicollinearity

It is well known that unstability of solutions to small changes in inputs c auses many problems in numerical computations. Existence, uniqueness and st ability of solutions are important features of mathematical problems. Probl ems that fail to satisfy these conditions are called imposed. The purpose o f this study is to remind briefly some methods of solution to ill-posed pro blems and to see the impacts or connections of these techniques to some sta tistical methods. (C) 2000 Elsevier Science Inc. All rights reserved. AMS c lassification: 65F35; 62J07.