SWSamp is a general purpose package to provide a suite of functions for the sample size calculations and power analysis in a Stepped Wedge Trial. Contains functions for closed-form sample size calculation (based on a set of specific models) and simulation-based procedures that can extend the basic framework.

There are two ways of installing `SWSamp`

. A "stable" version is packaged and binary files are available for Windows and as source. To install the stable version on a Windows machine, run the following commands

```
install.packages("SWSamp",
repos=c("http://www.statistica.it/gianluca/R",
"https://cran.rstudio.org",
"https://www.math.ntnu.no/inla/R/stable"),
dependencies=TRUE
)
```

Note that you need to specify a vector of repositories - the first one hosts `SWSamp`

, while the second one should be an official CRAN mirror. You can select whichever one you like, but a CRAN mirror must be provided, so that `install.packages()`

can also install the "dependencies" (e.g. other packages that are required for `SWSamp`

to work). The third one is used to install the package `INLA`

, which can be used to perform simulation-based sample size calculations using a Bayesian approach. This process can be quite lengthy, if you miss many of the relevant packages.

To install from source (e.g. on a Linux machine), run

```
install.packages("SWSamp",
repos=c("http://www.statistica.it/gianluca/R",
"https://cran.rstudio.org",
"https://www.math.ntnu.no/inla/R/stable"),
type="source",
dependencies=TRUE
```

The second way involves using the "development" version of `SWSamp`

- this will usually be updated more frequently and may be continuously tested. On Windows machines, you need to install a few dependencies, including Rtools first, e.g. by running

```
pkgs <- c("foreach", "doParallel", "iterators", "parallel", "Matrix","lme4","INLA","Rtools","devtools")
repos <- c("https://cran.rstudio.com", "https://www.math.ntnu.no/inla/R/stable")
install.packages(pkgs,repos=repos,dependencies = "Depends")
```

before installing the package using `devtools`

:

```
devtools::install_github("giabaio/SWSamp")
```

Under Linux or MacOS, it is sufficient to install the package via `devtools`

:

```
install.packages("devtools")
devtools:install_github("giabaio/SWSamp")
```

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