Re: [ccp4bb] am I doing this right?

2021-10-17 Thread Frank von Delft
Thanks, I learnt two things now - one of which being that I'm credited with coining that word!  Stap me vittals... If it's single photon events you're after, isn't it quantum statistics where you need to go find that prior?  (Or is that what you're doing in this thread - I wouldn't be able to

Re: [ccp4bb] am I doing this right?

2021-10-17 Thread Gergely Katona
Dear James, No, the prior does not have to be a gamma distribution. As I understand (and I am out of my comfort zone here), the reason for choosing gamma is indeed convenience. I believe this convenience is rapidly lost as the Bayesian network gets complicated and any hope of an analytical expr

Re: [ccp4bb] am I doing this right?

2021-10-17 Thread Nave, Colin (DLSLtd,RAL,LSCI)
Hi James For the case under consideration, isn't the gamma distribution the maximum entropy prior i.e. a default with minimum information content. Colin -Original Message- From: CCP4 bulletin board On Behalf Of James Holton Sent: 17 October 2021 18:25 To: CCP4BB@JISCMAIL.AC.UK Subject:

Re: [ccp4bb] am I doing this right?

2021-10-17 Thread Jurgen Bosch
The EM and Cryo-EM world might have something to say about that perhaps. Isn’t RIP phasing coming from what you are describing as well? Just curious, Jürgen __ Jürgen Bosch, PhD, MBA Center for Global Health & Diseases Case Western Reserve University htt

Re: [ccp4bb] am I doing this right?

2021-10-17 Thread James Holton
Thank you Gergely.  That is interesting! I don't mind at all making this Bayesian, as long as it works! Something I'm not quite sure about: does the prior distribution HAVE to be a gamma distribution? Not that that really narrows things down since there are an infinite number of them, but is t

Re: [ccp4bb] am I doing this right?

2021-10-17 Thread James Holton
Well Frank, I think it comes down to something I believe you were the first to call "dose slicing". Like fine phi slicing, collecting a larger number of weaker images records the same photons, but with more information about the sample before it dies. In fine phi slicing the extra informatio

Re: [ccp4bb] am I doing this right?

2021-10-17 Thread Kay Diederichs
If you write/analyze/improve a data-reduction program in crystallography, then these questions are important: how to estimate the intensity of a Bragg spot by evaluating the counts in the pixels of the signal area, and those of the background area? When calculating mean and standard deviation of

Re: [ccp4bb] am I doing this right?

2021-10-17 Thread Frank Von Delft
James, I've been watching the thread with fascination, but also the confusion of wild ignorance. I've finally realised why. What I've missed is: what exactly makes the question so important? I've understood what brought it up, if course, but not the consequence of getting it wrong. Frank Sen