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  1. Request For Comments
  2. RFC-333

Correctly use "Sigma" and "Err" everywhere

    Details

    • Type: RFC
    • Status: Implemented
    • Resolution: Done
    • Component/s: DM, TCT
    • Labels:

      Description

      As I recently learned in John Swinbank's review of PhotoCalib, the DPDD says this about "Err" and "Sigma":

      For all catalog data, we will employ a convention where estimates of standard errors have the suffix Err, while the estimates of inherent widths of distribution (or functions in general) have the suffix Sigma

      On the other hand, we use Sigma in many places where we really mean Err. For example, our source tables are littered with _fluxSigma and _xySigma, which are documented as "1-sigma uncertainty". Our database schema is mixed in this regard as well (e.g. raSigma, an "uncertainty" and uPSFluxSigma a "Standard deviation of the distribution" in the DiaSource table).

      This RFC is to gather consensus about how best to sanitize our usage of these terms in the stack and related software and interfaces. The concrete propose here is to replace all incorrect uses of Sigma with Err, and vice versa in all code below lsst_distrib and in cat.

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            Hide
            swinbank John Swinbank added a comment -

            Fully implemented by the completion of DM-10935.

            Show
            swinbank John Swinbank added a comment - Fully implemented by the completion of DM-10935 .
            Hide
            Parejkoj John Parejko added a comment -

            Russell Owen: that was already fixed in DM-10933, it just needs to be merged (the agreement to merge happened just before the all hands and I missed it).

            Lets keep discussion about remaining work on the relevant epic: DM-10932

            Show
            Parejkoj John Parejko added a comment - Russell Owen : that was already fixed in DM-10933 , it just needs to be merged (the agreement to merge happened just before the all hands and I missed it). Lets keep discussion about remaining work on the relevant epic: DM-10932
            Hide
            rowen Russell Owen added a comment -

            The code has been fixed. Now I'm looking at our documentation. I think the only thing that needs changing is C++ style guide entry 3-34 says to use "Sigma" not "Err" for error. Could somebody please suggest new wording for this entry? I'm really not sure what to say...for instance do we still recommend "Var" as a suffix for variance?

            Show
            rowen Russell Owen added a comment - The code has been fixed. Now I'm looking at our documentation. I think the only thing that needs changing is C++ style guide entry 3-34 says to use "Sigma" not "Err" for error. Could somebody please suggest new wording for this entry? I'm really not sure what to say...for instance do we still recommend "Var" as a suffix for variance?
            Hide
            Parejkoj John Parejko added a comment -

            Implementation ticket filed as Epic DM-10932, with associated stories.

            NOTE! When the schema and code tickets (DM-10935, DM-10936) are implemented, this will be a breaking change for backwards compatibility, including old reference catalogs and previously processed data. We recommend that publicly provided reference catalogs be copied and marked "deprecated: for use with LSST stack < v??", and that updated catalogs be provided.

            Show
            Parejkoj John Parejko added a comment - Implementation ticket filed as Epic DM-10932 , with associated stories. NOTE! When the schema and code tickets ( DM-10935 , DM-10936 ) are implemented, this will be a breaking change for backwards compatibility, including old reference catalogs and previously processed data. We recommend that publicly provided reference catalogs be copied and marked "deprecated: for use with LSST stack < v??", and that updated catalogs be provided.
            Hide
            Parejkoj John Parejko added a comment -

            Thanks for clarification, Tim Jenness and John Swinbank. I will work with Simon Krughoff tomorrow to file the appropriate tickets.

            Show
            Parejkoj John Parejko added a comment - Thanks for clarification, Tim Jenness and John Swinbank . I will work with Simon Krughoff tomorrow to file the appropriate tickets.

              People

              • Assignee:
                Parejkoj John Parejko
                Reporter:
                Parejkoj John Parejko
                Watchers:
                Andy Salnikov, Gregory Dubois-Felsmann, Jim Bosch, John Parejko, John Swinbank, Kian-Tat Lim, Krzysztof Findeisen, Paul Price, Robert Lupton, Russell Owen, Simon Krughoff, Tim Jenness, Zeljko Ivezic
              • Votes:
                1 Vote for this issue
                Watchers:
                13 Start watching this issue

                Dates

                • Created:
                  Updated:
                  Resolved:
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