WinBUGS is part of the BUGS project, which aims to make practical MCMC methods available to applied statisticians. See the main BUGS page for a summary of the different versions of BUGS available.

WinBUGS can use either a standard  'point-and-click' windows interface for controlling the analysis, or can construct the model using a graphical interface called DoodleBUGS. WinBUGS is a stand-alone program, although it can be called from other software. For a version that BUGS (BRugs) that sits within the R statistical package, see the OpenBUGS site.

We require that users register with usto obtain unrestricted use, and in particular give us some idea of the intended use of the program. This information provides valuable feedback to ourselves and our funders.

Watch WinBUGS - The Movie! for a short Flash illustration of the basic steps of running WinBUGS. (This movie features WinBUGS 1.3 - when you've watched it you will understand why WinBUGS 1.4 includes scripts to avoid all the clicking and pointing!)

All the documentation specific to WinBUGS is available on-line and is packaged with the program.

Pdf versions of both the WinBUGS 1.4 manual (which DOES NOT include features in the 1.4.1 patch) and the GeoBUGS manual (which DOES feature the 1.4.1 patch) can now be downloaded, as can PDF versions of Volume 1, Volume 2, and Volume 3 of the examples.

Please read the LICENSE AGREEMENT for WinBUGS, before downloading anything.

The single file you need is WinBUGS14.exe, and selecting the link will yield a dialog box inviting you to save the file onto your system.

WinBUGS 1.1 and WinBUGS 1.2 are still available for those with historical interests. WinBUGS 1.3 and its key are also available and may still be useful if problems are obtained with WinBUGS 1.4 and for running PKBUGS Version 1 (see below).

For installation, run the file WinBUGS14.exe. One way to do this is as follows:

1. Exit all other programs currently running (particularly if using Windows XP)
2. Copy WinBUGS14.exe to your computer
3. Go into Explore and double click on WinBUGS14.exe
4. Follow the instructions in the dialog box
5. You should have a new directory called WinBUGS14 within Program Files
6. Inside the WinBUGS14 directory is a program called WinBUGS14.exe
7. Right-click on the pretty WinBUGS icon, select 'create shortcut', then drag this shortcut to the desktop.
8. Double click on WinBUGS14.exe to run WinBUGS14.

If you have problems after installation, check again that you did not have programs running. You could also try disabling any virus checker.

If all else fails, you can download a zipped version of the whole file structure and unzip it into Program Files or wherever you want it.

WinBUGS is free, but has absorbed a lot of time and grant money over the last 15 years or so. We need to keep our employers happy with our time spent on the project, and it helps if we can keep track of how many people are downloading it and where they come from. It is also very helpful to have an idea of what it is being used for.

Please fill in the registration form and return it to us. We will then e-mail you the key which will remove the restrictions in WinBUGS 1.4. After following the instructions given in the key, check that the Keys.ocf file in ..\WinBUGS14\Bugs\Code\ has been updated. (Some people have found they need to re-boot the machine to complete installation of the key.)

Please note that the key currently being issued is valid until December 31st 2006. You will be sent a link for a new key before this one expires.

A free patch for upgrading to version 1.4.1 is now available. Click here to obtain a full description and the patch file.

Some models that run in 1.3 are running slowly or not at all. Please let us have examples. This may be due to the change in the update order to graphical order, which has sorted out problems with forward sampling, but has introduced some new difficulties. We shall probably need to make adjustments to the adaptive slice sampler. (If your Trap message complains of problems with DFreeARS (Distribution-free adaptive rejection sampling), you could try changing to slice sampling for log-concave distributions - see manual for instructions.)

Etienne Rivot has pointed out that after a Trap, you can 'Save States' (model Menu), then reinitialise the model with these states. There may then, with luck, be a helpful proper error message!

Additions/corrections to WinBUGS 1.4 manual

• GeoBUGS 1.2 for spatial analysis
• PKBUGS for pharmacokinetic modelling
• A new test version for Reversible Jump MCMC.
• Suites of S-plus/R functions for convergence diagnostics, suitable for use with any version of BUGS.
• WinBUGS can be remotely called from a variety of packages (although note that one can now run BUGS from within R using BRugs).
• We now have a website exclusively for development and distribution of extensions to WinBUGS - see the WinBUGS development site and Dave Lunn's forthcoming ISBA Bulletin article for more details.

From a technical perspective, WinBUGS uses the software philosophy of component-oriented progamming, which means the program is constructed from a set of cooperating components. This set is not closed, and so the functionality of WinBUGS can be continuously extended by developing new components: see the OpenBUGS site for the latest developments.