make.time.factor: Make time-varying dummy variables from time-varying factor variable
Description
Create a new dataframe with time-varying dummy variables
from a time-varying factor variable. The time-varying
dummy variables are named appropriately to be used as a
set of time dependent individual covariates in a
parameter specification
dataframe containing set of factor variables
with names composed of var.name prefix and times suffix
var.name
prefix for variable names
times
numeric suffixes for variable names
intercept
the value of the factor variable that
will be used for the intercept
delete
if TRUE, the origninal time-varying factor
variables are removed from the returned dataframe
Value
x: a dataframe containing the original data (with
time-varying factor variables removed if delete=TRUE) and
the time-varying dummy variables added.
Details
An example of the var.name and times is
var.name="observer", times=1:5. The code expects to find
observer1,...,observer5 to be factor variables in x. If
there are k unique levels (excluding ".") across the time
varying factor variables, then k-1 dummy variables are
created for each of the named factor variables. They are
named with var.name, level[i], times[j] concatenated
together where level[i] is the name of the facto level i.
If there a m times then the new data set will contain
m*(k-1) dummy variables. If the factor variable includes
any "." values these are ignored because they are used to
indicate a missing value that is paired with a missing
value in the encounter history. Note that it will create
each dummy variable for each factor even if a particular
level is not contained within a factor (eg observers 1 to
3 used but only 1 and 2 on occasion 1).