Hi,

I've managed to do a pretty good job of confusing myself in my latest
attempt to understand the likelihood stuff, and was hoping that I could
get some pointers as to what I'm misunderstanding.

1. How does one determine the amplitude and phase to use from a given
likelihood surface?  Some of the papers I've read refer to using the
centroid; others seem to be talking about using the location of the
maxima.  Is there any guidance for when you'd use one instead of the
other, or is this one of those "try both and see which works best"
situations?

2. How do you get the HL coefficients out of a likelihood surface?  The
only way I could think of to do this would be to pick up the likelihood
values over the full phaser circle for a constant amplitude, and fit a
2-term fourier series to the ln of those values.  But this approach feels
more like a work-around than anything else (and would lead to the same
point in complex space having two difference likelihoods for a centric
reflection), so I'm fairly sure there's a better way to do this (although
I don't have any ideas what that would be).  SigmaA weights might be a
possibility, but as far as I know they wouldn't work for all cases (MAD
and SAS don't have native amplitude measurements).

Thanks in advance for any help,

Pete

Pete Meyer
Fu Lab
BMCB grad student
Cornell University

Reply via email to