how to treat weak data

Jinsong Liu jinsong at THYMINE.RUTGERS.EDU
Tue Jun 18 10:30:21 EST 1996


I have question on how to treat weak data in the refinement. I was using X-PLOR
in refinement, the refinement got stuck at R-free at 0.36, and R at 0.29. But 
when I looked at the map, the map looks very good, so I think the model can't
be wrong. The statistics of R is bad, the R ( both test set and working set) 
value weak reflection is about 120%,  for the rest R is in the range 20%-40%.
There are about 350 weak reflection which have such bad R value.
I am afraid if I need to down-weight the weak reflection or do some thing else.
I don't know if it is possible in X-PLOR to use a cut-off weight for weaker 
reflection. I have checked the data reduction, it seemed I can not do too much
for it. The reason for the stuck I think is because the refinement tried to fit
the model to those weak reflections which then bias the model.

Any help will be greatly appreciated.

jinsong



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