The spduration package provides functions to estimate split-population duration regression models in which only a subset of the population is at risk for failure, while the remainder is immune, or cured, from the possibility of experiencing a failure event. In practice, this class of models also may produce better performance in sparse data with few actual failure events.

## Details

The main function spdur is used to estimate the model objects with class spdur.

Postestimation tools include predict.spdur, for calculating fitted values with arbitrary data and for several probabilities that might be of interest, as well as plot.spdur for visual display of model fit.

## References

Boag, J.W. 1949. Maximum Likelihood Estimates of the Proportion of Patients Cured by Cancer Therapy.'' <http://www.jstor.org/stable/2983694>

Berkson, J. and Gage, R.P. Survival Curve for Cancer Patients Following Treatment.'' <http://www.jstor.org/stable/2281318>

Leisch, Friedrich. 2009. Creating R Packages: A Tutorial.''

Schmidt, Peter and Witte, Ann Dryden. 1989. Predicting Criminal Recidivism Using "Split Population" Survival Time Models.'' <doi:10.1016/0304-4076(89)90034-1>

Svolik, Milan. 2008. Authoritarian Reversals and Democratic Consolidation.'' American Political Science Review.