An overview

The bsitar package provides an interface for Bayesian implementation of Super Imposition by Translation and Rotation (SITAR) growth model. The SITAR is a shape-invariant nonlinear mixed effect model that fits a natural cubic spline mean curve and aligns individual-specific growth curves to the underlying mean curve via a set of random effects: the size, timing and intensity. The bsitar package package is a front-end to the R package brms which uses the Stan program to performing full Bayesian inference for a range of regression specifications including hierarchical multivariate modeling.


To install the latest release version from CRAN use


The current developmental version can be downloaded from GitHub via

if (!requireNamespace("remotes")) {

The bsitar internally depends on the brms package which can be installed from the CRAN as


The latest developmental version of brms can be downloaded from GitHub as


Note that the brms, and hence the bsitar too, are based on Stan, therefore
a C++ compiler is required. The program Rtools (available on comes with a C++ compiler for Windows. On Mac, you should install Xcode. For further instructions on how to get the compilers running, see the prerequisites section on