Last data update: 2014.03.03

R: Estimates survival using landmark estimation
 surv.land.obs R Documentation

## Estimates survival using landmark estimation

### Description

Estimates the probability of survival past some specified time using landmark estimation for an observational study setting

### Usage

```surv.land.obs(tl, dl, tt, landmark, short = NULL, z.cov = NULL, var = FALSE,
conf.int = FALSE, ps.weights, weight.perturb = NULL, perturb.ps = FALSE,
perturb.vector = FALSE, bw = NULL)
```

### Arguments

 `tl` observed event time of primary outcome, equal to min(T, C) where T is the event time and C is the censoring time. `dl` event indicator, equal to I(T

### Details

See documentation for delta.land.obs for details.

### Value

A list is returned:

 `S.estimate` the estimate of survival at the time of interest, hat{S}(t) = P(T>t) `S.var ` the variance estimate of hat{S}(t); if var = TRUE or conf.int = TRUE `conf.int.normal.S` a vector of size 2; the 95% confidence interval for hat{S}(t) based on a normal approximation; if conf.int = TRUE `conf.int.quantile.S` a vector of size 2; the 95% confidence interval for hat{S}(t) based on sample quantiles of the perturbed values, described above; if conf.int = TRUE `perturb.vector` a vector of size x where x is the number of columns of the provided weight.perturb matrix (or x=500 if weight.perturb is not provided); the perturbed values of hat{S}(t); if perturb.vector = TRUE and either var=TRUE or conf.int = TRUE

Layla Parast

### References

Parast, L. & Griffin B.A. (2015). Landmark Estimation of Survival and Treatment Effects in Observational Studies, in press.

### Examples

```data(example_obs)
W.weight = ps.wgt.fun(treat = example_obs\$treat, cov.for.ps = as.matrix(example_obs\$Z))
example_obs.treat = example_obs[example_obs\$treat == 1,]
#executable but takes time
#surv.land.obs(tl=example_obs.treat\$TL, dl = example_obs.treat\$DL, tt=2, landmark = 1,
#short = cbind(example_obs.treat\$TS,example_obs.treat\$DS), z.cov = example_obs.treat\$Z,
#ps.weights = W.weight[example_obs\$treat == 1])
```

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