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Re: [ccp4bb]: I to F's

Related to this discussion is some nice reading material from the book of D.S. Sivia "DATA ANALYSIS A bayesian tutorial" p77-80. In this section of the book, the problem of taking the square root of a (negative) intensity is addressed. By using Bayes theorem and the prior knowledge that intensities must be positive, estimates are obtained for the structure factor and sigma. It is graphically illustrated for good reflections, poor but positive intensity reflections and for reflections with negative intensities.

Arjan Snijder

Arjan Snijder
Lab. of Biophysical Chemistry
University of Groningen
Nyenborgh 4
9747 AG Groningen
tel +31 (0) 50 3634396
fax +31 (0) 50 3634800