Greetings, I have the following problem: I want to compare a "parameter trajectory", i.e. a series of real numbers (representing equidistant samples of a time-varying parameter) produced by some "model", to a reference trajectory, measured from the real world, in order to get a rating of how good the model that produced the first trajectory is. Ok, so I use the RMS of the difference between the two trajectories at each sample. Then I have another model, producing another trajectory, leading to another RMS-value. Good. Now I want to clame that the two models are "equally good" on the basis of the RMS-values being similar, and require some sort of significance test to support this claim. But I can't assume normal distribution in this case since the values are squared (or can I?) so with my limited knowledge of statistics I'm stuck... Any help is appreciated! regards - Jonas PS I apologize for posting a question entirely unrelated to R but any R-related answers are of course welcome! -- Jonas Beskow, Ph.D. Tel: +46 8 790 8965 Centre for Speech Technology Fax: +46 8 790 7854 KTH beskow at speech.kth.se SE-10044 Stockholm, Sweden www.speech.kth.se/~beskow