Recent discussion on how to compare regression lines was really = enlightening. As far as I understood, the discussion was about comparing = slopes in linear regressions.=20
=20 I have similar problems in comparing non-linear regression lines. Here, = it goes what I want to compare. I have shrub biomass and pine seedling = density data collected in 160 50-m^2 plots. I used non-linear regression = (y =3D b0*(1-exp(-b1^x)) to model the cumulative seedling density = against shrub biomass. I am interested to test if this regression curve = (observed pattern) differs from another similar curve (a reference = model), generated by using Poisson cumulative distribution function. My = questions are: how to compare these two non-linear regression lines or = the coefficients there in? Are the methods described in Zar's book and = elsewhere, more commonly used for comparing slopes in linear regression, = also applicable for non-linear regression lines? =20 =20 Any suggestion will be highly appreciated.=20 =20 Jay Sah ________________________________________ Jay P. Sah, Ph.D. Post-doctoral Research Associate Southeast Environmental Research Center University Park, OE-148 Florida International University Miami, FL 33199, USA Tel. 305-348-1658; Fax. 305-348-4096 Web: http://www.fiu.edu/~sahj ________________________________________
