[daip] [!7296]: AIPS - OMFIT and strange chi2 values

[Michael Bietenholz]

Michael Bietenholz updated #7296
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OMFIT and strange chi2 values
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           Ticket ID: 7296
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/7296
           Full Name: Michael Bietenholz
               Email: mbieten at yorku.ca
             Creator: User
          Department: AIPS Data Reduction
       Staff (Owner): -- Unassigned --
                Type: Issue
              Status: Open
            Priority: Default
                 SLA: NRAO E2E
      Template Group: Default
             Created: 22 September 2015 08:35 PM
             Updated: 22 September 2015 10:24 PM
      Resolution Due: 30 September 2015 08:35 PM (7d 22h 10m)



No, this is a different issue.  The problem is that, at least with NOISE(1)=0, the "real" Chi2 comes out
at exactly DOF*2, regardless of how well or poorly the model fits, which doesn't seem right (the factor of 2 is
the lesser problem, the more serious issue is that if you change the model so that the rms residual
is 10x worse, the Chi2 remains unchanged whereas it should be 100x higher!)

I haven't had a chance to try and look through the code yet - the thing I don't understand is that
it didn't behave this way for my SN1993J data, although even there something probably wasn't right with the
"real chi2" since it seemed insensitive to the value of NOISE(1).

                michael

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