Compute weights for censored regression via the inverted probability of censoring principle.

`IPCweights(x, maxweight = 5)`

A vector of numeric weights.

- x
an object of class

`Surv`

.- maxweight
the maximal value of the returned weights.

Inverse probability of censoring weights are one possibility to fit
models formulated in the *full data world* in the presence of censoring,
i.e., the *observed data world*, see van der Laan and Robins (2003) for
the underlying theory and Hothorn et al. (2006) for an application to
survival analysis.

Mark J. van der Laan and James M. Robins (2003),
*Unified Methods for Censored Longitudinal Data and Causality*,
Springer, New York.

Torsten Hothorn, Peter Buehlmann, Sandrine Dudoit,
Annette Molinaro and Mark J. van der Laan (2006), Survival ensembles.
*Biostatistics* **7**(3), 355--373.

Peter Buehlmann and Torsten Hothorn (2007),
Boosting algorithms: regularization, prediction and model fitting.
*Statistical Science*, **22**(4), 477--505.