JAGS tutorial at useR! 2017

I am giving a pre-conference tutorial on JAGS at useR! 2017 in Brussels on 4 July. You can see the outline of the tutorial on the conference website along with the other tutorials being given the same day.

This is my first pre-conference tutorial. Last year I gave a three day course on JAGS at the University of Zurich, so I have plenty material. My main problem is not over-filling the 3-hour time slot.

You can always make it faster…

… but sometimes you just need a good example to show you how. Saana Isojunno from the University of Saint Andrews wrote to me with an example that stopped working when she upgraded from JAGS 3.4.0 to JAGS 4.2.0. Saana’s model showed the classic signs of a memory leak. Compilation was very slow and memory consumption increased until all available RAM was used and the process was killed by the operating system. Continue reading

PyJAGS

Editors note: I am very pleased to announce that Tomasz Miąsko has created a Python interface to JAGS. The rest of this post is by Tomasz.

Nowadays Python users certainly cannot complain about a lack of MCMC packages. We have emcee, PyMC, PyMC3, and PyStan to mention a few. Recently this list was extended by one more; PyJAGS – a Python interface to JAGS. JAGS is a program for analysis of Bayesian hierarchical models using Markov Chain Monte Carlo (MCMC) simulation, quite often used from within the R environment with the help of the rjags package. The PyJAGS package offers Python users a high-level API to JAGS, similar to the one found in rjags. Current rjags users interested in migrating to Python should feel at home. Of course, other interested in doing Bayesian data analysis may also find PyJAGS useful. Continue reading

JAGS 4.0.0 is released

After a long gestation period, JAGS 4.0.0 was finally released last week. If you go to the project page on Sourceforge then you should see an appropriate download link for your platform (binary packages for Windows and Mac OS X; source tarball for other platforms). Binary packages are also available for some Linux distributions. See the JAGS homepage for details.

Mac users should note that you need OS X 10.9 or later (i.e. Mavericks, Yosemite, or El Capitan). Older releases are no longer supported.

The rjags package for R has been updated to work with the new release of JAGS. It is not yet uploaded to CRAN, and the version of rjags that is available on CRAN (rjags_3-15) does not work with JAGS 4.0.0. However, you can download rjags_4-3 from Sourceforge. Again, binary packages are available for Windows (.zip) and Mac OS X (.tgz).

What’s new in JAGS 4.0.0 part 3/4: R-style features

The BUGS language is syntactically very similar to R and there are several packages that allow R users to interface with the JAGS library. When you are using both R and JAGS simultaneously, small differences between the languages can be frustrating. Consequently there is some pressure to narrow the gap between the two languages.  There are some things we cannot change, such as the parameterization of the distributions, but there is a tendency for JAGS to become more R-like with each release. JAGS 4.0.0 introduces a few more R-like features. Continue reading