knotsWCE {WCE}

Obtain the placement of the knots used for splines in WCE models

Description

This function extracts the knots placement for the spline function used to fit the WCE models.

Usage

knotsWCE(x)

Arguments

x

A WCE object.

Details

The function returns a list with one element if the WCE object was fitted without covariates and two if the WCE object was fitted with covariates. The first element is a matrix of estimated coefficients for the artificial D variables (see Sylvestre and Abrahamowicz, 2009). Each row of the matrix corresponds to a model with the number of knots specified in WCE. The second element of the list is a matrix of estimated covariate coefficients. Similarly, each row of the matrix corresponds to a model with the number of knots specified in WCE.

Value

Returns a list of vectors indicating the placement of the knots used in the spline function of each of the models fitted in the WCE object.

References

Sylvestre, M. P., & Abrahamowicz, M. (2009). Flexible modeling of the cumulative effects of time-dependent exposures on the hazard. Statistics in medicine, 28(27), 3437-3453.

Examples

wce <- WCE(drugdata, "Cox", 1, 90, constrained = "R", id = "Id", event = "Event",
start = "Start", stop = "Stop", expos = "dose", covariates = c("age", "sex"))
knotsWCE(wce)