[3dem] Resolution Criteria in 3D data processing (cryo-EM)

[Marin van Heel]

Dear All,

Impressive as the cryo-EM results of the resolution resolution may be, a 
fundamental statistical error has persisted in the literature that 
affects almost all cryo-EM quality metrics (FSC-0.143, FSC 0.5; DPR 45, 
SSNR, Gold Stardust FSC, etc ...)  One of the very few survivors of this 
methodology onslaught is the FSC 1/2 bit criterion. The numerical 
resolution values for practically all published structures have no 
absolute meaning and can therefore not be compared to each other. The 
error goes back to a misinterpretation of basic statistics made in the 
1970s and pervaded virtually all popular cryo-EM quality metrics.  It 
may frustrate many of you to have to change your way of thinking or the 
programs you are using, but that is what science requires you to do now. 
Alternatively - following strict scientific standards - you can try 
prove us wrong with real scientific arguments (carefully read our paper 
before you start criticizing). Even if 99% of cryo-EM practitioners use 
incorrect metrics, that does not make the metrics right! Science is not 
a democracy ...  We are of course aware that with this paper we are 
refuting a huge number of methodological papers all at once, with many 
people involved who will undoubtedly be left frustrated. If that is of 
any help, I also feel frustrated that it took me (us) far too long to 
get to the core of the matter so as to resolve these issues once and for 
all. On the positive side, we can now all be relieved of the eternal and 
repetitive FSC jokes at cryo-EM meetings!

For now, good night and have a good weekend!

Marin

our BiorXiv contribution ca be found here: 
https://www.biorxiv.org/content/early/2017/11/24/224402


-- 
==============================================================

     Prof Dr Ir Marin van Heel

     Laboratório Nacional de Nanotecnologia - LNNano
     CNPEM/LNNano, Campinas, Brazil

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             marin.vanheel(A_T)lnnano.cnpem.br
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     Emeritus Professor of Cryo-EM Data Processing
     Leiden University
     Mobile NL: +31(0)652736618

     Emeritus Professor of Structural Biology
     Imperial College London
     Faculty of Natural Sciences
     email: m.vanheel(A_T)imperial.ac.uk

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