If I understand your problem correctly, you wish to do curve fitting in PERL using large ammounts of data and then detect excepts that are identified. Yes, there are a number of statistical methods to accomplish that (which I know very little about).

• The statistical modules for PERL might help. Check them out here. (or try the Math modules here).
• I know there is a book that talks about specific curve fitting examples. Ah, here it is. I believe if you know the math behind the subject, then you can create your own algorithm with the help of this book (and contribute to CPAN!).
• May be you don't have to do the curve fitting in PERL. You could use a statistics package for that if there is one that you use and have code/scripts already written for. PERL can be your data parsing and results presentation system and coordinate the work of the curve fitting program.

-- termix