drc: mixture – R documentation

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drc

mixture

Fitting binary mixture models

Description

'mixture' fits a concentration addition, Hewlett or Voelund model to data from binary mixture toxicity experiments.

Usage

mixture(object, model = c("CA", "Hewlett", "Voelund"), start, startm, control = drmc())

Arguments

`object`	object of class 'drc' corresponding to the model with freely varying EC50 values.
`model`	character string. It can be "CA", "Hewlett" or "Voelund".
`start`	optional numeric vector supplying starting values for all parameters in the mixture model.
`startm`	optional numeric vector supplying the lambda parameter in the Hewlett model or the eta parameters (two parameters) in the Voelund model.
`control`	list of arguments controlling constrained optimisation (zero as boundary), maximum number of iteration in the optimisation, relative tolerance in the optimisation, warnings issued during the optimisation.

Details

The function is a wrapper to drm, implementing the models described in Soerensen et al. (2007). See the paper for a discussion of the merits of the different models.

Currently only the log-logistic models are available. Application of Box-Cox transformation is not yet available.

Value

An object of class 'drc' with a few additional components.

Author(s)

Christian Ritz

References

Ritz, C. and Streibig, J. C. (2014) From additivity to synergism - A modelling perspective Synergy, 1, 22–29.