standard deviations for cell constants

Tricia Takahara takahara at athena.mit.edu
Wed Jun 5 17:30:05 EST 1996


Hi -
Has anyone ever reported or determined a standard deviation
for unit cell constants determined by using an image plate?
We have a Mar and use DENZO to process the data and would like
to report some sort of standard deviation for our cell constants
in our next paper.  The problem is that we use a capillary mount
and move the plate in and out when the crystal starts to decay
and we have to translate it and re-center it.  This means we
have to refine the distance several times during the DENZO
processing.  This results in slightly different cell constants
for different sections of the data (the constants vary by a 
tenth of an angstrom or so).  It has been suggested that we
just average the cell constants and do a standard deviation
calculation by hand, but we are not sure this is correct because
we vary so many parameters during the processing of the frames.
Any comments/ideas/suggestions would be appreciated.  Thanks!

-Tricia Takahara
takahara at mit.edu 




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