# emfrail_dist: Distribution parameters for emfrail In frailtyEM: Fitting Frailty Models with the EM Algorithm

## Description

Distribution parameters for emfrail

## Usage

 ```1 2``` ```emfrail_dist(dist = "gamma", theta = 2, pvfm = -1/2, left_truncation = FALSE, basehaz = "breslow") ```

## Arguments

 `dist` One of 'gamma', 'stable' or 'pvf'. `theta` A starting value for the 'outer' maximization with respect to the frailty parameter θ. Must be >0. `pvfm` Only relevant if `dist = 'pvf'` is used. It determines which PVF distribution should be used. Must be larger than -1 and not equal to 0. `left_truncation` Logical. Whether the data set represents left truncated survival times. `basehaz` A character string which determines how the baseline hazard is calculated. The default is "breslow", but other possible options are "weibull", "exponential" "gaussian", "logistic", "lognormal" or "loglogistic".

## Details

The `theta` argument must be positive. In the case of gamma or PVF, this is the inverse of the frailty variance, i.e. the larger the `theta` is, the closer the model is to a Cox model. When `dist = "pvf"` and `pvfm = -0.5`, the inverse Gaussian distribution is obtained. For the positive stable distribution, the γ parameter of the Laplace transform is θ / (1 + θ), with the alpha parameter fixed to 1.

## Value

An object of the type `emfrail_dist`, which is mostly used to denote the supported frailty distributions in a consistent way.

`emfrail, emfrail_control`

## Examples

 ```1 2 3 4 5``` ```emfrail_dist() # Compound Poisson distribution: emfrail_dist(dist = 'pvf', theta = 1.5, pvfm = 0.5) # Inverse Gaussian distribution: emfrail_dist(dist = 'pvf') ```

### Example output

```Loading required package: survival
\$dist
 "gamma"

\$theta
 2

\$pvfm
 -0.5

\$left_truncation
 FALSE

attr(,"class")
 "emfrail_dist"
\$dist
 "pvf"

\$theta
 1.5

\$pvfm
 0.5

\$left_truncation
 FALSE

attr(,"class")
 "emfrail_dist"
\$dist
 "pvf"

\$theta
 2

\$pvfm
 -0.5

\$left_truncation
 FALSE

attr(,"class")
 "emfrail_dist"
```

frailtyEM documentation built on Sept. 22, 2019, 5:05 p.m.