[phenixbb] phenix and weak data
Pavel Afonine
pafonine at lbl.gov
Mon Dec 10 13:08:52 PST 2012
Hi Ed,
>>> I had always assumed that experimental sigmas were somehow lumped
>> into the alpha and beta parameters (esp. given your discussion in
>> section 2.3). In principle they could be, right?
>>
>> Yes, they could be.
> I would like clarification on this. (...)
>
> Alpha/beta are calculated in individual resolution shells. How can you
> "lump" experimental variance that varies by two orders of magnitude for
> individual reflections into a single parameter?
I'm sorry for being unclear (often email happens to be a poor way to
express what you actually mean, unless you have heaps of time to write
it lawyer style. There is always a room for reader to imagine unsaid.
Sometimes it works, sometimes it doesn't.).
Anyways, extending my phrase above to better reflect what I actually
meant: "Yes, they could be, to some extent (approximation). Surely, a
proper way is to have sigmas in the formula explicitly, as I stated in
previous email of that thread. Whether that makes any practically useful
difference is debatable, and yet to answer."
> I also wonder if introducing experimental uncertainty into Lunin's ML
> target is even possible without fundamentally altering it.
It is possible, and depends how fundamentally you want to alter it.
All the best,
Pavel
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