Data quality: Difference between revisions

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* it depends on the multiplicity (unfortunately often called redundancy): the higher the multiplicity, the higher R<sub>merge</sub> becomes
* it depends on the multiplicity (unfortunately often called redundancy): the higher the multiplicity, the higher R<sub>merge</sub> becomes
* it assesses data consistency, not the quality of the reduced data
* it assesses data consistency, not the quality of the reduced data
This has been discussed by Diederichs and Karplus<ref name="DiKa97">K. Diederichs and P.A. Karplus (1997). Improved R-factors for diffraction data analysis in macromolecular crystallography. Nature Struct. Biol. 4, 269-275 [http://strucbio.biologie.uni-konstanz.de/strucbio/files/nsb-1997.pdf]</ref>), who suggest a multiplicity-independant version called R<sub>meas</sub>, which unfortunately is not used by everyone because the formula gives higher values than R<sub>merge</sub>. R-factors for data quality assessment were also suggested by Diederichs and Karplus, and Weiss and Hilgenfeld <ref name="WeHi97">M.S. Weiss and R. Hilgenfeld (1997) On the use of the merging R-factor as a quality indicator for X-ray data. J. Appl. Crystallogr. 30, 203-205 [http://dx.doi.org/10.1107/S0021889897003907]</ref>. Weiss <ref name="We01">M.S. Weiss (2001) Global indicators of X-ray data quality. J. Appl. Cryst. 34, 130-135 [http://dx.doi.org/10.1107/S0021889800018227]</ref> showed that these R-factors are indeed strongly correlated with the quality of the data.
This has been discussed by Diederichs and Karplus<ref name="DiKa97">K. Diederichs and P.A. Karplus (1997). Improved R-factors for diffraction data analysis in macromolecular crystallography. Nature Struct. Biol. 4, 269-275 [http://strucbio.biologie.uni-konstanz.de/strucbio/files/nsb-1997.pdf]</ref>, who suggest a multiplicity-independant version called R<sub>meas</sub>, which unfortunately is not used by everyone because the formula gives higher values than R<sub>merge</sub>. R-factors for data quality assessment were also suggested by Diederichs and Karplus, and Weiss and Hilgenfeld <ref name="WeHi97">M.S. Weiss and R. Hilgenfeld (1997) On the use of the merging R-factor as a quality indicator for X-ray data. J. Appl. Crystallogr. 30, 203-205 [http://dx.doi.org/10.1107/S0021889897003907]</ref>. Weiss <ref name="We01">M.S. Weiss (2001) Global indicators of X-ray data quality. J. Appl. Cryst. 34, 130-135 [http://dx.doi.org/10.1107/S0021889800018227]</ref> showed that these R-factors are indeed strongly correlated with the quality of the data.


== References ==
== References ==
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