[R-sig-eco] Fitting a Weibull with a 0 dose

Thank you for the help!  My data is not binomial, so it is more like the ryegrass data from the drc library. The model:  ryegrass.m2 - drm(rootl ~ conc, data = ryegrass, fct = W1.4())I think this will solve my problems!Katie  [[alternative HTML version deleted]]

[R-sig-eco] EC50 Calculations using Insect Size

I have insect size measurements that I fit to a Weibull curve to determine EC50.  This is my model fit:model=nls(y~SSweibull(x,asym,drop,lrc,pwr)) I need to use the untreated buffer samples as the maximum size (the left most asymptope).  If I put the doses as 0,1,2,4,8,16,32,64,128 ppm, I get