utilitiesForSurvivalTrials {rpact} R Documentation

## Survival Helper Functions for Conversion of Pi, Lambda, Median

### Description

Functions to convert pi, lambda and median values into each other.

### Usage

```getLambdaByPi(piValue, eventTime = 12L, kappa = 1)

getLambdaByMedian(median, kappa = 1)

getHazardRatioByPi(pi1, pi2, eventTime = 12L, kappa = 1)

getPiByLambda(lambda, eventTime = 12L, kappa = 1)

getPiByMedian(median, eventTime = 12L, kappa = 1)

getMedianByLambda(lambda, kappa = 1)

getMedianByPi(piValue, eventTime = 12L, kappa = 1)
```

### Arguments

 `piValue, pi1, pi2, lambda, median` Value that shall be converted. `eventTime` The assumed time under which the event rates are calculated, default is `12`. `kappa` A numeric value > 0. A `kappa != 1` will be used for the specification of the shape of the Weibull distribution. Default is `1`, i.e., the exponential survival distribution is used instead of the Weibull distribution. Note that the Weibull distribution cannot be used for the piecewise definition of the survival time distribution, i.e., only `piecewiselambda` (as a single value) and `kappa` can be specified. This function is equivalent to `pweibull(t, shape = kappa, scale = 1 / lambda)` of the `stats` package, i.e., the scale parameter is `1 / 'hazard rate'`. For example, `getPiecewiseExponentialDistribution(time = 130, piecewiseLambda = 0.01, kappa = 4.2)` and `pweibull(q = 130, shape = 4.2, scale = 1 / 0.01)` provide the sample result.

### Details

Can be used, e.g., to convert median values into pi or lambda values for usage in `getSampleSizeSurvival` or `getPowerSurvival`.

### Value

Returns a `numeric` value or vector will be returned.

[Package rpact version 3.1.0 Index]