acidiq {drc} | R Documentation |
Data from an experiment where the chemicals acifluorfen and diquat tested on Lemna minor. The dataset has 7 mixtures used in 8 dilutions with three replicates and 12 common controls, in total 180 observations.
data(acidiq)
A data frame with 180 observations on the following 4 variables.
cell
dose1
pct1
rgr1
The dataset is analysed in S{o}rensen et al (2006). Hewlett's symmetric model seems appropriate for this dataset.
The dataset is kindly provided by Nina Cedergreen, Department of Agricultural Sciences, Royal Veterinary and Agricultural University, Denmark.
S{o}rensen, H. and Cedergreen, N. and Skovgaard, I. M. and Streibig, J. C. (2006) An isobole-based statistical model and test for synergism/antagonism in binary mixture toxicity experiments, Statistical Ecology and Environmental Statistics, 13. ?–??.
## Fitting the model with freely varying ED50 values model1 <- multdrc(rgr1~dose1, pct1, data=acidiq, collapse=list(~factor(pct1),~1,~1,~factor(pct1) - 1), boxcox=TRUE) summary(model1) ## Fitting the concentration addition model model1ca <- mixture(rgr1~dose1, pct1, data=acidiq, collapse=~factor(pct1), model="CA", boxcox=TRUE) anova(model1ca) # comparison to model with freely varying e parameter summary(model1ca) ## Fitting the Hewlett model model1h <- mixture(rgr1~dose1, pct1, data=acidiq, collapse=~factor(pct1), model="Hewlett", boxcox=TRUE) anova(model1h) # comparison to a model with freely varying e parameter anova(model1ca, model1h) # rejecting concentration addition summary(model1h) ## Fitting the Voelund model model1v <- mixture(rgr1~dose1, pct1, data=acidiq, collapse=~factor(pct1), model="Voelund", boxcox=TRUE) anova(model1v) # comparison to a model with freely varying e parameter summary(model1v) rm(model1, model1ca, model1h, model1v)