daphnids {drc} | R Documentation |
The number of immobile daphnids –in contrast to mobile daphnids– out of a total of 20 daphnids was counted for several concentrations of a toxic substance.
data(daphnids)
A data frame with 16 observations on the following 4 variables.
dose
no
total
time
24h
48h
The same daphnids were counted at 24h and later again at 48h.
Nina Cedergreen, Royal Veterinary and Agricultural University, Denmark.
## Fitting a model with different parameters ## for different curves model1.daphnids <- multdrc(no/total~dose, time, weights=total, data=daphnids, fct=l2(), type="binomial") ## Goodness-of-fit test anova(model1.daphnids) ## Fitting a model with a common intercept parameter model2.daphnids <- multdrc(no/total~dose, time, weights=total, data=daphnids, fct=l2(), type="binomial", collapse=list(~1, ~time)) rm(model1.daphnids, model2.daphnids)