[NeXus-committee] RFC variants and esd

[Peterson, Peter F.]

Another thing to add in on this topicŠI thought we had already agreed on
was that uncertainties is the field with "_errors" appended rather than
"_esd". 
http://download.nexusformat.org/doc/html/classes/base_classes/NXdata.html

P^2

On 10/24/13 4:56 PM, "Pete Jemian" <prjemian at gmail.com> wrote:

>Wrote this comment too quickly.
>
>On 10/24/2013 12:50 PM, Pete Jemian wrote:
>> Fundamentally, a field would have an attribute that names a child group
>> in which the uncertainty (single or plural) is described with fields.
>
>Look at the figure below this URL:
>
>A field with numerical data (such as "I") has an uncertainty attribute
>that gives the name of another field (such as "Idev") in the same group
>containing numerical value(s) for the uncertainty.  The name of the
>uncertainty field is specified by the user.  That field contains the
>estimated uncertainty associated with the first field (such as I +/-
>Idev).  For fields with multiple uncertainties or other complexities
>that contribute to the uncertainty, a subgroup, perhaps an NXnote, can
>be created to contain those fields.  The name of that subgroup is given
>in the components attribute of the uncertainty field.
>
>In the example shown, I is the measured intensity, Idev is the estimated
>uncertainty and has several contributions each of which are documented
>in the I_uncertainties group: Johnson noise, shot noise, and estimated
>standard deviation (esd).  For the purposes of data analysis, I and Idev
>are used and the rest are likely ignored.
>
>The example following this suggests a way to represent multiple
>uncertainties such as standard deviation and standard error.  It does
>not recommend a way to handle that data, just how to represent it.
>Suggested is that the first item in the list is the one to use in
>analysis.
>
>Pete
>
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