Comparing journal impact factors across subject fields?

[Ackermann, Eric]

I am doing a study in which I would like to compare the journal impact factors and rankings across subject fields (as given by the Journal Citation Reports). Given the skewed nature of the data and the differences in the citation habits of each subject field, I've been searching for a way to do this so that I am still comparing apples to apples (i.e., like results to like results), perhaps similar to z-scores for normal distributions. I've been looking in the literature for such a means but without much luck. Can anyone suggest an article (or two) that would explain such a method (if it exists) and demonstrate how it is used?

Many thanks for your help in this matter.

Regards,