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.

In the past, we have required that users register with us to obtain unrestricted use, in particular to give us some idea of the intended use of the program. This information has provided valuable feedback to ourselves and our funders. However, we no longer require users to register and the key for unrestricted use (of WinBUGS 1.4.x) can be downloaded from here.

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 1.4.3 patch) and the GeoBUGS manual (which DOES feature the 1.4.3 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 files you need are WinBUGS14.exe (selecting the link will yield a dialog box inviting you to save the file onto your system) and the key for unrestricted use, which is free.

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.

Note: There appears to be a problem with installing WinBUGS and/or various patches in Windows Vista. Vista doesn't seem to like anyone overwriting files in the "C:\Program Files" directory (regardless of permissions). Hence we recommend that WinBUGS be installed elsewhere, e.g. "C:\".

If all else fails (for example with a 64-bit machine), you can download a zipped version of the whole file structure and unzip it into Program Files or wherever you want it. WinBUGS makes no changes to the Registry.

WinBUGS is free, but has absorbed a lot of time and grant money over the last two decades. We have tried to keep our employers happy with our time spent on the project by keeping track of how many people are downloading it and where they come from. It has also been very helpful to have an idea of what it is being used for. This information has, in the past, been collected via a registration process whereby users enter their details and a key for unrestricted use of the software has been sent to them via email (free of charge). However, as development shifts more and more towards OpenBUGS, we have decided that it is time to do away with this registration process and simply allow direct access to the key (which will no longer expire at the end of each year)...

Please click here to download the key for unrestricted use. 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.)

A free patch for upgrading to version 1.4.3 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

• The syntax given in the GeoBUGS manual for defining the scale of a map is wrong: In the manual we say that the syntax is:
  xScale: 1000
  yScale: 1000
  whereas, in fact, it should be
  Xscale: 1000
  Yscale: 1000

• 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 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.