Additional formula
objects to specify
predictors of non-linear and distributional parameters.
Formulas can either be named directly or contain
names on their left-hand side.
The following are distributional parameters of specific families
(all other parameters are treated as non-linear parameters):
sigma
(residual standard deviation or scale of
the gaussian
, student
, lognormal
exgaussian
, and asym_laplace
families);
shape
(shape parameter of the Gamma
,
weibull
, negbinomial
, and related
zero-inflated / hurdle families); nu
(degrees of freedom parameter of the student
family);
phi
(precision parameter of the beta
and zero_inflated_beta
families);
kappa
(precision parameter of the von_mises
family);
beta
(mean parameter of the exponential componenent
of the exgaussian
family);
quantile
(quantile parameter of the asym_laplace
family);
zi
(zero-inflation probability);
hu
(hurdle probability);
zoi
(zero-one-inflation probability);
coi
(conditional one-inflation probability);
disc
(discrimination) for ordinal models;
bs
, ndt
, and bias
(boundary separation,
non-decision time, and initial bias of the wiener
diffusion model).
All distributional parameters are modeled
on the log or logit scale to ensure correct definition
intervals after transformation.
See 'Details' for more explanation.