# samplesizeCMH:
Sample Size Calculation for the Cochran-Mantel-Haenszel Test

by Paul W. Egeler M.S.

## Description

This package provides functions relating to power and sample size
calculation for the CMH test. There are also several helper functions
for interconverting probability, odds, relative risk, and odds ratio
values.

Please see the package vingettes for more information on how this
package is used.

### The Cochran Mantel Haenszel
Test

The **Cochran-Mantel-Haenszel test** (CMH) is an
inferential test for the association between two binary variables, while
controlling for a third confounding nominal variable. Two variables of
interest, *X* and *Y*, are compared at each level of the
confounder variable *Z* and the results are combined, creating a
common odds ratio. Essentially, the CMH test examines the
*weighted* association of *X* and *Y*. The CMH test
is a common technique in the field of biostatistics, where it is often
used for case-control studies.

### Sample Size Calculation

Given a target power which the researcher would like to achieve, a
calculation can be performed in order to estimate the appropriate number
of subjects for a study. The `power.cmh.test`

function
calculates the required number of subjects per group to achieve a
specified power for a Cochran-Mantel-Haenszel test.

### Power Calculation

Researchers interested in estimating the probability of detecting a
true positive result from an inferential test must perform a power
calculation using a known sample size, effect size, significance level,
*et cetera*. The `power.cmh.test`

function can compute
the power of a CMH test, given parameters from the experiment.

## Installation

Downloading and installing the package from GitHub is facilitated by
`devtools`

.
To do so, type the following into your R console:

```
install.packages("devtools")
devtools::install_github("pegeler/samplesizeCMH")
```