Changes from WinBUGS to OpenBUGS

• The methods for selecting updaters for nodes has been extensively changed.
• The syntax of the scripting commands changed in OpenBUGS, and many new scripting commands have been added. The script command in the model menu can now be applied to a subset of selected script commands to allow a mix of scripting and interactive menu selection while fitting a model. An R function to convert WinBUGS scripts to OpenBUGS scripts is available UserContributedCode
• Updater Options have been added to the Model Menu. These allow a user to select (after compiling) the updater to be used for each node. An updater can also be disabled by a user to force the use of a different option.
• Options were added to the Info menu to better display the updaters used for different nodes.
• OpenBUGS also runs on Linux, though only in command-line mode and only on PC (x86) platforms.
• OpenBUGS can be run in a fully interactive manner from R via the BRugs R package (see UserContributedCode).
• Externalize and Internalize commands have been added to the model menu in OpenBUGS. These commands create a snap shot of a current OpenBUGS session so it can be restored and edited/continued at a later time. Scripting is still a better option for re-producible results, as Externalize/Interalize can create very large files.
• The specification of random number starting seeds changed in OpenBUGS. A user can now select 1 of 14 initial states for the RNG that produce sequences that do not overlap for >=10^{12} draws.
• The dirichlet distribution has been renamed ddirich from ddirch to match the R naming convention.
• A dloglik distribution was added for more clear model statements when implementing the ‘zero’ Poisson trick for generic likelihoods and priors. Note that in earlier releases of OpenBUGS, the distribution was named dgeneric rather than dloglik.
• OpenBUGS can handle both censored and truncated distributions. Previous versions of BUGS, e.g. WinBUGS, could only handle censoring, using the I(,) notation, although this could sometimes be exploited to trick BUGS into truncating. To avoid any confusion, OpenBUGS allows truncation via the notation T(lower, upper) and censoring via C(lower, upper). The I(lower, upper) notation is still allowed for censoring (for the sake of backwards compatibility) but is deprecated. For more information on the subtle differences between censoring and truncation, and on the use of I(,), please see here. Note that truncation is currently only an option for the following densities: dbeta(), dexp(), dnorm(), dpois(), dt() and dweib().
• Several new functions and distributions have been added to OpenBUGS (e.g., eigen.vals, integral, gammap, ode, prod, p.valueM, solution ).
• A search option has been added to the Help Menu for searching all manuals or examples.
• An option was added to the OpenBUGS Model menu that will convert a ‘checked’ model to latex format.
• A Show Data option has been added to the Info menu.
• New “density strips” plot added to the Compare menu, which illustrates sampled distributions by smoothly-varying shading.
• Initial values for the mv.car distribution are now checked for the zero-sum constraint. This causes some old examples to fail unless their inits files are changed.

Changes to GeoBUGS

• The car.normal distribution weights vector length is now checked for consistency with the length of adj. WinBUGS would execute successfully if weights was longer.