Holger,
One program which may be of use is MicroFit, available at
http://www.ifr.ac.uk/MicroFit/default.html . I have never used it, and
don't know anyone who has, but it looks like it should do what you want.
It performs parameter estimations (growth rate, lag time, etc.) as well
as statistical analyses between two data sets.
Good luck,
Vince Mulholland
