A data transformation of normalizing ratio data by using a locally weighted polynomial regression (typically after a log transformation). The regression can be performed on log ratios resulting from the relation of two data sets versus the average log intensity data from the same two data sets or it can be performed on raw or log transformed values from one data set versus values from another. The goal could be to remove intensity-dependent dye-specific effects from the set of pair wise ratios. This method can be applied globally, or limited by one or more specified criteria.