I'm pretty new to WinBUGS, although I'm reasonably knowledgeable on 
MCMC and Bayesian statistics.  The BUGS team ask for ideas for 
improvements and new features, and I thought I might try them out on 
this list.  That way, I might get some support for my ideas, or even 
better be told that these features are somewhere in BUGS already.

1.  What about a list of recently used files in the File menu?  This 
is common in Windows software and very helpful.

2.  From BUGS I can save graphics into a compound document or paste 
into something like Word, but how can I edit such graphs?  What 
format are they in?  Can we have graphs in a format understood by 
other systems, e.g. postscript?  Or can we have access to the data 
defining the graph, like coordinates of points on curves?

3.  I can sort of save the whole MCMC output in a form readable by 
CODA, but I don't seem able to recreate it in a later BUGS session.  
So suppose I do a run and save some results like means or density 
plots of some nodes.  Then later I want to start up BUGS again and 
look at some other nodes or some other kinds of output like 
quantiles.  Because the MCMC run itself is not saved, I can't do 
this.  I have to do a fresh run.  Not only is this wasteful (and 
perhaps very time consuming), but then the data on which the new 
outputs are derived are different from the data on which the previous 
outputs were calculated.  What about an option to save the status 
from one WinBUGS run to another as a kind of workspace?

4.  A related question.  I want to be able to try various different 
versions of a model, perhaps with different priors.  I don't seem to 
be able to change any of the data once the model is compiled.  I have 
to go back and input the entire model and data (in its modified form) 
from scratch.  I understand that recompilation would be necessary, 
but why does BUGS seem to forget everything once it has compiled?  
Can we have the facility to re-open the current model specification, 
input a few changes to data, then recompile?  Can we even be 
allowed to reopen the model specification, change the model and then 
not have to input data that have not changed?

Tony O'Hagan
----
Professor A O'Hagan            Email: [log in to unmask]
Department of Probability and Statistics
University of Sheffield        Phone: +44 114 222 3773
Hicks Building
Sheffield S3 7RH, UK           Fax:   +44 114 222 3759


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