Usage
mixture(formula, curve, collapse, weights, data = NULL, boxcox = FALSE,
bcAdd = 0, varPower = FALSE, startVal, fct = l4(), na.action = na.fail,
robust = "mean", type = "continuous", cm = NULL, logDose = NULL,
control = mdControl(), model = "Hewlett", startVal2)
Arguments
formula
a symbolic description of the model to be fit. Either of the form 'response $~$ dose' or as a data frame with response value
in first column and dose in second column.
curve
a numeric vector (percentages!) containing the grouping of the data.
collapse
a formula starting with a tilde, specifying the model for the b parameter in the logistic model (the only 'free' parameter).
weights
a numeric vector containing weights.
data
a data frame containing the variables in the model. This argument is not optional!
boxcox
logical or numeric. If TRUE the optimal Box-Cox transformation is applied to the model.
If FALSE (the default) no Box-Cox transformation is applied. If numeric the specified value is used in the Box-Cox transformation.
bcAdd
a numeric value specifying the constant to be added on both sides prior to Box-Cox transformation. The default is 0.
varPower
logical. If TRUE the variance is modelled as a power function of the mean.
If FALSE (the default) no variance modelling is applied.
startVal
an optional numeric vector containing start values for all parameters in the model. Overrules any self starter function.
fct
a list with three or 5 elements specifying the non-linear
function, the accompanying self starter function, the names of the parameter in the non-linear function and, optionally, the first and second derivatives.
na.action
a function which indicates what should happen when the data contain 'NA's. The default is 'na.fail'. To omit 'NA's use
'na.omit'.
robust
a character string specifying the rho function for robust estimation. Default is non-robust least squares estimation ("mean").
Available robust methods are: median estimation ("median"), least median of squares ("lms"), least trimmed squares ("lts"),
type
a character string specifying the data type: binomial and continuous are the only options currently.
cm
character string or numeric value specifying the level in curve corresponding to control measurements.
logDose
a numeric value or NULL. If log doses value are provided the base of the logarithm should be specified (exp(1) for the natural logarithm
and 10 for 10-logarithm).
control
a 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.
model
a character string. It can be "CA", "Hewlett" or "Voelund".
startVal2
an optional numeric vector supplying the lambda parameter in the Hewlett model or the eta parameters (two parameters)
in the Voelund model.