Re: [ccp4bb] Another scaling question

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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

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From: James Holton JMHolton {- at -} LBL {- dot -} GOV
Date: 2010-06-24

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Subject: Re: Another scaling question
From: Jim Pflugrath Jim {- dot -} Pflugrath {- at -} RIGAKU {- dot -} COM
Date: 2010-06-24

It might be instructive to draw a precession-like diagram of your
reflections in reciprocal space. Remember that reciprocal space dimensions
are generally in reciprocal Angstrom and volumes raise those dimensions to
the third power. Thus (1/12)^3 to (1/15)^3 is not a big volume.

How many reflections should you have between 15 Angstrom and 12 Angstrom?
Between 12 Angstrom and 4 Angstrom?

Suppose only 4 unique reflections exist between 12 and 15 Angstrom. What
happens to your completeness if you are missing just one of them?

-----Original Message-----
From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Simon
Kolstoe
Sent: Thursday, June 24, 2010 10:05 AM
To: CCP4BB@JISCMAIL.AC.UK
Subject: [ccp4bb] Another scaling question

Dear CCP4bb,

I am still playing around scaling two datasets together and have noticed
another interesting behavior in scala. If I scale all my data (from 1.5A to
51A) I get 100% completeness in my outer shell, 98% in my inner shell and
99.9% overall, stats that I am normally quite happy with. I tend to also
look at the table in the log file which in this case reports above 98%
completeness in all shells between 1.5 and 4.7A. Rmerges are 0.054 overall
with 0.29 in the outer shell, which again I think is OK.

However I then ran scala again in an attempt to scale with the strongest
overlapping reflections in my two datasets, so limited the resolution to
between 15A and 4A. Now when I look at my completeness I get 97% overall,
but only 32% in the highest 15-12A shell! Is something funny going on in the
program or am I really missing 70% of my data in this resolution, and if so
how come the scala run with all the data doesn't report this? I am now
worrying that all the data I previously thought was complete might be
lacking many lower resolution reflection!

Thanks,

Simon

CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: Stuck refinement
From: James Holton JMHolton {- at -} LBL {- dot -} GOV
Date: 2010-06-24

Next message:
Subject: Re: How to run UPPSALA-mapman in PBS?
From: Hailiang Zhang zhangh1 {- at -} UMBC {- dot -} EDU
Date: 2010-06-24