varian is a free, open source R package for variability analysis using Bayesian inference.

It provides a formula interface in R to define a multilevel model for a variable with repeated measures, in addition to standard multilevel features such as fixed effects and a random intercepts/slopes, the residual variance is a random variable by ID. The latent residual variance estimates are then used as predictors in a regression of another outcome.

Getting Started

At its core, varian uses Stan to estimate the models.

Prerequisites

R

R version 3.1.1 or later is required. You can download the latest version of R here:

http://www.r-project.org/

Tools

Stan and the varian package rely on being able to compile C++ code.

• For Windows, download and install Rtools at http://cran.r-project.org/bin/windows/Rtools/
• For Mac, make sure you have the latest version of Xcode installed. The installation instructions for rstan provide more details.
• For Linux, make sure you have a recent version of ge++ or clang++.

RStan

Install the latest version of the rstan package, which you can do from CRAN now. That page also lists more detailed directions for getting the necessary tools installed.

```R
install.packages("rstan", dependencies = TRUE)
```

Install varian

You can install:

• the latest stable release (0.2.2) from CRAN

  install.packages("varian", dependencies = TRUE)

• the latest development version from github

  install.packages("devtools")
  devtools::install_github("ElkhartGroup/varian")

Learn about the theory

See our open access pre-print on the arXiv http://arxiv.org/abs/1411.2961.

More

• If you find a bug or have a feature request, please let us know on the issue tracker: https://github.com/ElkhartGroup/varian/issues.

• Have questions or need support? Email us at info@elkhartgroup.com and mention "varian" in the subject.