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Hello,<br>
<br>
<blockquote cite="mid:D0FA7440.1214%25gzhu@hwi.buffalo.edu"
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<div>I have a data set for refinement at 3.8A (outshell I/sigma
~1.0). When I processed the data, I kept anomalous data I+/I-.
Because at that time I think I might have anomalous signal. But
later I found that the protein coordinated with wrong metal, so
I don�t really have anomalous scatters. I have good model from
high resolution data.�</div>
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<div>When I refined the structure, I found that refined against
I+/I- give lower R/Rfree (23.0%/27.0%) �than against Imean
(25.1%/28.3%). When I used I+/I-, I knew I doubled
reflections/parameters ratio. I also let Phenix both X-ray
stereochemistry/ADP weight. The refined models have similar
geometry. So should I use I+/I- for refinement since it gives
lower R factor?<br>
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</blockquote>
<br>
you cannot compare R-factors calculated using different sets of
reflections, they are simply not comparable. So 23.0%/27.0% versus
25.1%/28.3% doesn't really mean anything in this case.<br>
<br>
If data set is not anomalous then you can use
"force_anomalous_flag_to_be_equal_to=False" so that phenix.refine
uses Fobs_mean = (Fobs(+) - Fobs(-))/2 in refinement.<br>
<br>
Pavel<br>
<br>
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