Get named vector of coefficients for renewal objects.
renewalCoef(object, ...)an object, there are methods for several classes, see Details.
further arguments to be passed to renewalNames, usually
something like target = "weibull".
This is a convenience function for constructing named vector of coefficients for renewal count models. Such vectors are needed, for example, for starting values in the model fitting procedures. The simplest way to get a suitably named vector is to take the coefficients of a fitted model but if the fitting procedure requires initial values, this is seemingly a circular situation.
The overall idea is to take coefficients specified by object and
transform them to coefficients suitable for a renewal count model as
specified by the arguments "...". The provided methods eliminate the
need for tedius manual preparation of such vectors and in the most common
cases allow the user to do this in a single line.
The default method extracts the coefficients of object using
co <- coef(object) (an error is raised if this fails). It prepares a
named numeric vector with names requested by the arguments in "..."
and assigns co to the first length(co) elements of the prepared
vector. The net effect is that the coefficients of a model can be initialised
from the coefficients of a nested model. For example a Poisson regression
model can be used to initialise a Weibull count model. Of course the non-zero
shape parameter(s) of the Weibull model need to be set separately.
If object is from class glm, the method is identical to the
default method.
If object is from class renewalCoefList, its elements are
simply concatenated in one long vector.
Kharrat T, Boshnakov GN, McHale I, Baker R (2019). “Flexible Regression Models for Count Data Based on Renewal Processes: The Countr Package.” Journal of Statistical Software, 90(13), 1--35. doi:10.18637/jss.v090.i13 .