tvc creates a time interaction variable that can
be used in a coxph model (or any other model with time
interactions)
Usage
tvc(data, b, tvar, tfun = "linear", pow = NULL)
Arguments
data
a data frame
b
the non-time interacted variable's name
tvar
the time variable's name
tfun
function of time that btvc was multiplied by.
Default is tfun = "linear". Can also be tfun
= "log" (natural log) and tfun = "power". If
tfun = "power" then the pow argument needs to be
specified
pow
if tfun = "power", then use pow to
specify what power to raise the time interaction to.
Value
a vector
Details
Interacts a variable with a specified function of time.
Possible functions of time include 'linear',
natural 'log', and exponentiated ('power').