Information content from Athena for Hamilton test?
Hi everyone, Just a quick question regarding the "Information Content" output in Athena's LCF window. I've recently been playing around with using the Hamilton test (as outlined in Scott Calvin's book "XAFS for Everyone") to interrogate my combinatorics results. As many of you will know, this requires an estimate of the number of independent measurements in the data, in order to determine the degrees of freedom and subsequently the "a" value for computing the Lower Incomplete Beta Function. Would Athena's value for "Information Content" be appropriate to use as an estimate of the number of independent measurements in this case? How is this value of "Information Content" determined in Athena? Thanks in advance. Will
HI Will,
I am not entirely sure how this value is determined in Athena, but the
number of independent data in a XANES fit is the data range divided by the
resolution. If you have a spectrum with a strong pre-edge peak, you can
determine the resolution from its width. Otherwise, the resolution is a
convolution of the core-hole broadening and the beamline energy resolution.
Athena gives a value that is very close to the value determined directly
from the width of a preedge peak.
Sincerely,
Wayne
On Sun, Apr 9, 2017 at 8:59 PM, Will Bennett
Hi everyone,
Just a quick question regarding the "Information Content" output in Athena's LCF window. I've recently been playing around with using the Hamilton test (as outlined in Scott Calvin's book "XAFS for Everyone") to interrogate my combinatorics results. As many of you will know, this requires an estimate of the number of independent measurements in the data, in order to determine the degrees of freedom and subsequently the "a" value for computing the Lower Incomplete Beta Function. Would Athena's value for "Information Content" be appropriate to use as an estimate of the number of independent measurements in this case? How is this value of "Information Content" determined in Athena?
Thanks in advance.
Will
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-- Wayne Lukens Staff Scientist Lawrence Berkeley National Lab
On 04/09/2017 11:59 PM, Will Bennett wrote:
How is this value of "Information Content" determined in Athena?
This is not explained well in the manual. The number Athena reports is the fitting range of the data divided by the core-hole lifetime of the edge measured. I am not certain that is especially well-justified, but it seems like a reasonable approximation. B -- Bruce Ravel ------------------------------------ bravel@bnl.gov National Institute of Standards and Technology Synchrotron Science Group at NSLS-II Building 743, Room 114 Upton NY, 11973 Homepage: http://bruceravel.github.io/home/ Software: https://github.com/bruceravel Demeter: http://bruceravel.github.io/demeter/
participants (3)
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Bruce Ravel
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Wayne Lukens
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Will Bennett