Chemometrics is a field of chemistry that studies the application of s
tatistical methods to chemical data analysis. In addition to borrowing
many techniques from the statistics and engineering literatures, chem
ometrics itself has given rise to several new data-analytical methods.
This article examines two methods commonly used in chemometrics for p
redictive modeling-partial least squares and principal components regr
ession-from a statistical perspective. The goal is to try to understan
d their apparent successes and in what situations they can be expected
to work well and to compare them with other statistical methods inten
ded for those situations. These methods include ordinary least squares
, variable subset selection, and ridge regression.