I seem to recall hearing Rsym first when I used the Xuong-Hamlin detector, since there were a substantial number of redundancies. There were two Rsyms, one called Rrms for the sqrt over the sum of weighted squared differences and and Rav for the linear summation of unweighted differences. This was for protein work.
I do recall Rmerge being more popular with the small molecule crystallographers. However, I also recall a difference between averaging over pairs of reflections that were or were not Bijvoet pairs, for even small differences in the anomalous scattering contributions. Bernie On Fri, January 18, 2008 9:29 am, R.M. Garavito wrote: > Kay, > > I beg to differ, but only in a pedantic way. Historically, Rsym > would refer to the agreement in symmetry-related reflections within a > single data set and Rmerge would be the agreement between 2 or more > data sets that were merged. This was the way we did it back in the > "old day" of precession photography and early oscillation > photography. While the terms seem synonymous today, the recent > thread "[ccp4bb] combine incomplete data sets" illustrates where such > a distinction is still relevant, where the "merging" is between data > collected under different experimental conditions (i.e., a different > crystal in a different orientation). > > Michael > > **************************************************************** > R. Michael Garavito, Ph.D. > Professor of Biochemistry & Molecular Biology > 513 Biochemistry Bldg. > Michigan State University > East Lansing, MI 48824-1319 > Office: (517) 355-9724 Lab: (517) 353-9125 > FAX: (517) 353-9334 Email: [EMAIL PROTECTED] > **************************************************************** > > > On Jan 18, 2008, at 10:15 AM, Kay Diederichs wrote: > >> Salameh, Mohd A., Ph.D. schrieb: >>> Hi everybody! >>> I will appreciate it if anybody can clarify to me the differences >>> between Rmerge and Rsym. Many thanks, M >> >> there is no difference - unfortunately there are two words for the >> same thing. "Rmerge" currently appears to be more in fashion. >> >> just my 2 cents, >> >> Kay >> -- >> Kay Diederichs http://strucbio.biologie.uni-konstanz.de >> email: [EMAIL PROTECTED] Tel +49 7531 88 4049 Fax 3183 >> Fachbereich Biologie, Universität Konstanz, Box M647, D-78457 Konstanz > >
