How about "rms.curv" function in the MASS library? Ravi.
----- Original Message ----- From: Ivone Figueiredo <[EMAIL PROTECTED]> Date: Monday, June 2, 2003 4:40 am Subject: [R] Help - Curvature measures of nonlinearity > Dear colleagues, > > Von Bertalanffy model is commonly adjust to data on fish length > (TL) and age (AGE) > TL= Linf*(1-exp(-K*(AGE-t0)). Linf, K and t0 are parameters of the > model.One main goal of the growth study is the comparison of > growth parameter estimates between sexes of the same species, or > estimates from different populations. > The realibility statistical tests normally applied are highly > dependent on the nonlinearity of the model used. > > Are there any developed routines in R ? to: > 1) calculate the maximum intrinsic curvature > 2) maximum parameter affecting curvature > 3) plot the two dimensional cross sections of confidence regions > (for different alpha values) of the model parameters > > Regards, > Ivone Figueiredo > [[alternate HTML version deleted]] > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
