In my opinion Rpim is not related directly to anomalous signal, so perhaps that is why there is some confusion.
Also I think some folks confused Rpim with Rrim. The latter is also called Rmeas. But once again, these are not related directly to anomalous signal. I do not find Rpim very useful for anything since when the data has high multiplicity Rpim gets very low, but as Michael Blum told me, "Precision does not trump accuracy." I would personally rather have accurate data than highly redundant but inaccurate data. I like to look at the deltaF / sigma(deltaF) value reported by SHELXC and other programs, where deltaF is ||F+| - |F-||. This might also be called <d"/sig>. There are other things to look at as well. Jim From: CCP4 bulletin board [CCP4BB@JISCMAIL.AC.UK] on behalf of Vijayakumar.B [vijaybioscie...@gmail.com] Sent: Tuesday, September 18, 2012 4:36 AM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Rpim and how its related to anomalous signal Dear CCP4BB users, I am very much interested to work in Anomalous scattering technique for macromolecular structure determination. I have already gone through some literature in which they have explained about a parameter called “Rpim”. I am little bit confused about Rpim values. Can anyone tell me about the use of this parameter in structure determination by anomalous techniques and how Rpim is related to anomalous signal? Thanks in advance With kind regards B. Vijayakumar
