# uncondPower2x2: Calculate power or sample size for any 2x2 test. In exact2x2: Exact Tests and Confidence Intervals for 2x2 Tables

## Description

The function `Power2x2` and `SS2x2` calculates the power or sample size for any 2x2 test, while the function `uncondPower2x2` calculates power for only tests supported by `uncondExact2x2Pvals`.

## Usage

 ```1 2 3 4 5 6 7``` ```Power2x2(n1, n2, theta1, theta2, alpha, pvalFunc, ...) uncondPower2x2(n1,n2, theta1, theta2, alpha, ...) SS2x2(theta1, theta2, alpha, pvalFunc, power=0.90, n1start=10, increaseby=1, n2.over.n1=1, maxiter=50, printSteps=TRUE, ...) ```

## Arguments

 `n1` sample size in group 1 `n2` sample size in group 2 `theta1` probability of success in group 1 `theta2` probability of success in group 2 `alpha` significance level `pvalFunc` function that inputs x1,n1,x2,n2 and outputs a p-value. `power` target power `n1start` value of n1 for first iteration `increaseby` positive integer, how much to increase n1 by for each iteration `n2.over.n1` ratio of n2/n1 `maxiter` maximum number of iterations `printSteps` logical, should the power and sample size be printed after each iteration? `...` arguments passed to `uncondExact2x2Pvals` (for `uncondPower2x2`), or to `Power2x2` (for `SS2x2`). Not used and saved for future use for `Power2x2`.

## Details

The function `Power2x2` is a very simple function to calculate power. It calculates power where rejection is when the p-value from `pvalFunc` is less than or equal to `alpha`. The function `SS2x2` repeatedly calls `Power2x2` as it increases the sample size, stopping when the power is greater than `'power'`.

The function `uncondPower2x2` is similar except the p-values are calculated by `uncondExact2x2Pvals`.

## Value

the power functions return only the power. The sample size function returns a list of class 'htest.power'.

For power and sample size for conditional exact tests (e.g., Fisher's exact tests) see `power2x2` and `ss2x2`. For power for the boundary-optimized rejection region (BORR) test see `powerBorr`.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17``` ```library(exact2x2) Power2x2(3,4,.1,.9,0.025, pvalFunc= function(x1,n1,x2,n2){ boschloo(x1,n1,x2,n2, alternative="greater", or=1,tsmethod="central", midp=TRUE)\$p.value } ) ## ## Not run: SS2x2(.1,.9,0.025, n1start=5, pvalFunc= function(x1,n1,x2,n2){ boschloo(x1,n1,x2,n2, alternative="greater", or=1,tsmethod="central", midp=TRUE)\$p.value } ) ## End(Not run) ```

### Example output

```Loading required package: exactci
 0.6908733
n1=5n2=5power=0.8221923711
n1=6n2=6power=0.904626841815

rejection determined by pvalFunc

power = 0.9046268
theta1 = 0.1
theta2 = 0.9
n1 = 6
n2 = 6
sig.level = 0.025
```

exact2x2 documentation built on Dec. 11, 2021, 9:43 a.m.