Dose-response profile of degradation of agrochemical using nasturtium
Estimation of the degradation profile of an agrochemical based on soil samples at depth 0-10cm from a calibration experiment.
data(nasturtium)
A data frame with 42 observations on the following 2 variables.
conca numeric vector of concentrations (g/ha)
weighta numeric vector of plant weight (mg) after 3 weeks' growth
It is an experiment with seven concentrations and six replicates per concentration. Nasturtium is sensitive and its weight reduces noticeable at low concentrations.
Racine-Poon (1988) suggests using a three-parameter log-logistic model.
Racine-Poon, A. (1988) A Bayesian Approach to Nonlinear Calibration Problems, J. Am. Statist. Ass., 83, 650–656.
nasturtium.m1 <- drm(weight~conc, data=nasturtium, fct = LL.3()) modelFit(nasturtium.m1) plot(nasturtium.m1, type = "all", log = "", xlab = "Concentration (g/ha)", ylab = "Weight (mg)")
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