nlformula: Manipulate a Nonlinear Model Formula
Description
Check and manipulate the formula for a nonlinear model, such as
specified in nlmer.
Arguments
mc
matched call from the calling function, typically
nlmer(). Should have arguments named
- formula:
- a formula of the form
resp ~ nlmod ~ meform
where resp is an expression for the response,
nlmod is the nonlinear model expression and
meform is the mixed-effects model formula.
resp can be omitted when, e.g., optimizing a design.
- data:
- a data frame in which to evaluate the model function
- start:
- either a numeric vector containing initial estimates
for the nonlinear model parameters or a list with components
nlpars:- the initial estimates of the nonlinear
model parameters
theta:- the initial estimates of the variance
component parameters
Value
a list with components
- "respMod"
- a response module of class
"nlsResp" - "frame"
- the model frame, including a terms attribute
- "X"
- the fixed-effects model matrix
- "reTrms"
- the random-effects terms object
Details
The model formula for a nonlinear mixed-effects model is
of the form resp ~ nlmod ~ mixed where
resp is an expression (usually just a name) for
the response, nlmod is the call to the nonlinear
model function, and mixed is the mixed-effects
formula defining the linear predictor for the parameter
matrix. If the formula is to be used for optimizing
designs, the resp part can be omitted.