# CVp2CV: Decompose CV(T) and CV(R) from 'pooled' CV of T/R In PowerTOST: Power and Sample Size for (Bio)Equivalence Studies

## Description

Helper function to calculate CV(T) and CV(R) from a pooled CV(T/R) assuming a ratio of the intra-subject variances.

## Usage

 `1` ```CVp2CV(CV, ratio = 1.5) ```

## Arguments

 `CV` ‘pooled’ CV of T and R (as ratio, not percent). `ratio` Ratio of the intra-subject variances `s^2(T)/s^2(R)`. May be a vector.

## Details

In case of knowing only the CV(T/R) f.i. from an ordinary cross-over you can calculate the components CV(T) and CV(R) assuming a ratio of the intra-subject variances.
The formula the function is based on:
`log(1.0 + CV^2) = (sWT^2 + sWR^2)/2`
Insert `sWT^2 = ratio * sWR^2` and solve for `sWR^2`.

## Value

Returns a numeric vector of the CV values for Test and Reference if only one ratio is given.
Returns a matrix with named columns `CVwT` and `CVwR` if ratio is given as vector.

D. Labes

## Examples

 ```1 2 3``` ```CVp2CV(0.4, ratio=2) # gives #  0.4677952 0.3225018 ```

### Example output

``` 0.4677952 0.3225018
```

PowerTOST documentation built on Jan. 18, 2021, 5:07 p.m.