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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.



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


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


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.

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

Install varian

You can install:

Learn about the theory

See our open access pre-print on the arXiv