Grouping procedure: Difference between revisions

Revision as of 12:17, 27 March 2013

Despite that RELION groups are NOT the same as defocus groups (see [[]])

Revision as of 12:13, 27 March 2013 (view source) Sjors Scheres (talk \| contribs) (Created page with "== What are groups for? == If you're going to group micrographs together it is important to understand what groups are used for inside RELION. Although you may be familiar wi...")		Revision as of 12:17, 27 March 2013 (view source) Sjors Scheres (talk \| contribs) (→‎What are groups for?) Newer edit →
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	== What ~~are groups for~~? ==		== What to base my gruping on? ==

	~~If you're going to group micrographs together it is important to understand what groups are used for inside RELION. Although you may be familiar with the concept of defocus groups in other packages,~~ RELION groups are NOT the same~~. Each particle has its own (possibly astigmatic) CTF model, and~~ groups ~~do not in any way affect the CTF models. Instead, for all particles inside each group, RELION will estimate an average power spectrum for the noise~~ (~~rlnSigma2Noise~~), as well as an average intensity scale factor. RELION will warn against using small numbers of particles inside a group, because these averages may become unstable. That in turn may lead to crashed runs that report errors like the sum of weights for certain particles being zero, or the scale factor being a strange number.		Despite that RELION groups are NOT the same as defocus groups (see [[]])