The `formula`

argument is treated exactly the same as in the
`survfit`

function.

Redistribution is recursive: redistribute the weight of the first
censored observation to all those with longer time, which may include
other censored observations. Then redistribute the next smallest and
etc. up to the specified `time`

value.
After re-distributing the weight for a censored observation to other
observations that are not censored, ordinary non-censored methods can
often be applied. For example, redistribution of the weights,
followed by computation of the weighted cumulative distribution
function, reprises the Kaplan-Meier estimator.

A primary use of this routine is illustration of methods or
exploration of new methods. Methods that use RTTR directly, such as
the Brier score, will often do these compuations internally.

A covariate on the right hand side of the formula causes
redistribution to occur within group; a censoring in group 1
redistributes weights to others in group 1, etc. This is appropriate
when the censoring pattern depends upon group.