Re: MAD / MLPHARE

[Ana Gonzalez <Ana@embl-hamburg.de>]

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On Thu, 30 Sep 1999 naismith@st-andrews.ac.uk wrote:

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> Hi 
> 
> Does anyone have a feel for whether MLPHARE will over estimate the FOM 
> from its MAD analysis?
> Secondly if you include the native and three wavelengths, given the
sites
> are all the same XYZ and differ only slightly in AOCC and OCC, how do we
> judge the FOM.

Most definitely. The more data sets at different wavelengths with the
same sites the fatter the FOMs get. If you don't want to bother
looking at the maps you can try looking at phase differences, or the
correlation between structure factors instead. 

Be careful about including the native in the MAD phasing. I wouldn't put
it in as the native, but as a derivative (with negative OCC and 0
AOCC). If you put it in as the native the error estimates  in the
differences with all the other data sets may be bigger than your
actual signal, unless the latter is truly gigantic. In that case the
FOMS do reflect the quality of the phases (both would be kind of bad)

Ana