# Prob.Covariate: Estimates P(TL <t0+tau | TL > t0, Z), i.e. given discrete... In landpred: Landmark Prediction of a Survival Outcome

## Description

This function calculates the probability that the an individual has the event of interest before t0 + tau given the discrete covariate and given the event has not yet occurred and the individual is still at risk at time t0; this estimated probability does not incorporate any information about the short term event information.

## Usage

 `1` ```Prob.Covariate(t0, tau, data, weight = NULL, short = TRUE, newdata = NULL) ```

## Arguments

 `t0` the landmark time. `tau` the residual survival time for which probabilities are calculated. Specifically, this function estimates the probability that the an individual has the event of interest before t0 + tau given the event has not yet occurred and the individual is still at risk at time t0. `data` n by k matrix, where k =3 or k=5. A data matrix where the first column is XL = min(TL, C) where TL is the time of the long term event, C is the censoring time, and the second column is DL =1*(TL

## Value

 `Prob` matrix of estimated probability for each value of the covariate; first column shows all covariate values and second column contains predicted probability at that covariate value `data` the data matrix with an additional column with the estimated individual probabilities; note that the predicted probability is NA if TL t0 `newdata` the newdata matrix with an additional column with the estimated individual probabilities; note that the predicted probability is NA if TL t0; if newdata is not supplied then this returns NULL

Layla Parast

## References

Parast, Layla, Su-Chun Cheng, and Tianxi Cai. Incorporating short-term outcome information to predict long-term survival with discrete markers. Biometrical Journal 53.2 (2011): 294-307.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13``` ```data(data_example_landpred) t0=2 tau = 8 Prob.Covariate(t0=t0,tau=tau,data=data_example_landpred) out = Prob.Covariate(t0=t0,tau=tau,data=data_example_landpred) out\$Prob out\$data newdata = matrix(c(1,1,1, 3,0,1, 4,1,1, 10,1,0, 11,0,1), ncol = 3, byrow=TRUE) out = Prob.Covariate(t0=t0,tau=tau,data=data_example_landpred,newdata=newdata) out\$Prob out\$newdata ```

landpred documentation built on Nov. 17, 2021, 1:06 a.m.