Comment

The issue of mean-centering has generated a lot of discussion. The point of view described by Belsley in his current article and in Belsley, Kuh, and Welsch (1980), in contrast with Marquardt and Snee (1975), Marquardt (1980), and Montgomery and Peck (1982), retraces much of the same ground as does the earlier debate between Smith and Campbell (1980) and Marquardt (1980). As often happens with extended discussions of this type, the resolution turns out to depend upon the somewhat different premises from which the parties have operated. We will attempt to be more explicit about our views than in the past, and to relate them to Belsley's position.