mixdrc {drc} | R Documentation |
'mixdrc' fits non-linear mixed models where random effects are assigned to some or all of the parameters.
mixdrc(object, random, data, startVal)
object |
an object of class 'drc'. |
random |
a character string specifying the random effects. Specification is as in nlme . |
data |
a data frame containing the variables in the model (not optional). |
startVal |
a numeric vector of initial parameter values for the fixed effects (optional). |
The function searches through a range of initial values in order to obtain convergence of the estimation procedure.
An object of classes 'drc' and 'nlme'.
Christian Ritz
Non-linear mixed models can be fitted using nlme
.
## First fitting a model without random effects model1 <- multdrc(SLOPE~DOSE, CURVE, data=PestSci, collapse=data.frame(HERBICIDE, 1, 1, HERBICIDE)) ## Then fitting the same model (the same fixed effects) ## but with random effects (assigned to d) model2 <- mixdrc(model1, random="d~1|CURVE", data=PestSci) compParm(model2, "e", "-") ## Fitting a model without random effects ## but with a Box-Cox transformation model3 <- multdrc(SLOPE~DOSE, CURVE, data=PestSci, collapse=data.frame(HERBICIDE, 1, 1, HERBICIDE), boxcox=TRUE) ## Then fitting the same model with random effects assigned to d model4 <- mixdrc(model3, random="d~1|CURVE", data=PestSci) compParm(model4, "e", "-") ## Fitting a model without random effects, but fixing the c parameter at 0 model5 <- multdrc(SLOPE~DOSE, CURVE, data=PestSci, collapse=data.frame(HERBICIDE, 1, 1, HERBICIDE), boxcox=TRUE, fct=LL.3()) ## Fitting the corresponding mixed model with random effects on d model6 <- mixdrc(model5, random="d~1|CURVE", data=PestSci)