Re: [sdpd] New poll for sdpd

[cockcroft...@gordon.cryst.bbk.ac.uk]

I agree with Jon's comments and Robin's too. For example, I would
be very hesitant about assigning a space group as, say, P3 from powder
data, but P2(1)/c one could be confidant about, especially if one knows
that one is dealing with a molecular system with 4 molecules with point
symmetry 1 per unit cell.
Re Robin's comment, then one has no choice but to vote "never" given the
wording of the question since it seems to imply 100% confidence levels.
I am not a statistician, but surely one needs a question that relates
to confidence limits (e.g. fully sure 99 cases out of 100 or whatever).
As pointed out earlier, even some single-crystal structures may be questionable
especially in the more "difficult" space groups (difficult because they
are less encountered by crystallographers and because of pseudo symmetry, etc.)
Finally, while I think this is a useful topic of discussion, please don't
overdo the "agent provocateur" bit Armel - I know it can be useful to start
discussion in the first place, but it should be done in moderation ;-)
    Jeremy Karl Cockcroft
(P.S. Hope this doesn't have to many typos in it now :-)

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