An object of class `survival`

stores survival probabilities. It is typically
returned by `Psm$sim_survival()`

or `PsmCurves$survival()`

; however, it can also
be constructed "manually" from existing data using the `survival()`

function as described below. The latter option is useful if survival modeling
has been performed by an `R`

package other than those that integrate with `hesim`

(
currently `flexsurv`

). In this case a simulation model can still be developed
by using `sim_stateprobs.survival()`

to compute simulated state probabilities and
then simulating quality-adjusted life-years and costs in a typical fashion.

```
survival(
data,
sample = "sample",
strategy_id = "strategy_id",
patient_id = "patient_id",
grp_id = "grp_id",
curve = "curve",
t = "t",
survival = "survival"
)
```

- data
A tabular object that can be coerced to a

`data.table`

with`as.data.table()`

.- sample
The name of the column corresponding to

`sample`

.- strategy_id
The name of the column corresponding to

`strategy_id`

.- patient_id
The name of the column corresponding to

`patient_id`

.- grp_id
The name of the column corresponding to

`grp_id`

.- curve
The name of the column corresponding to

`curve`

.- t
The name of the column corresponding to

`t`

.- survival
The name of the column corresponding to

`survival`

.

An object of class `survival`

that inherits from `data.table`

and contains
the following columns:

- sample
A random sample from the PSA.

- strategy_id
The treatment strategy ID.

- patient_id
The patient ID.

- grp_id
The subgroup ID.

- curve
One of the

`N`

-1 survival curves in an N-state partitioned survival model. Each curve corresponds to unique endpoint.- t
The time at which a survival probability is computed.

- survival
The probability of surviving to time

`t`

.

The object also contains a `size`

attribute that contains the elements
`n_samples`

, `n_strategies`

, `n_patients`

, `n_states`

, and `n_times`

denoting
the number of samples, treatment strategies, patients, health states, and times.

`survival`

objects are returned by methods in the `Psm`

and `PsmCurves`

classes. An example in which a `survival`

object is constructed "manually"
(presumably from a preexisting survival model fit using software other than `flexsurv`

)
is provided in the documentation to `sim_stateprobs.survival()`

.