Re: [PSAMP] PSAMP-INFO IE realtiveError

["Zseby, Tanja" <[e-mail]>]

Hi Thomas and Andrew,

I agree. But I also would add the confidence boundaries levels and the
small changes in PSAMP-PROTO as suggested in my first mail. 
But those changes were mainly agreed by the authors, correct? 

Kind regards
Tanja

> -----Original Message-----
> From: Andrew Johnson [mailto:[e-mail]]
> Sent: Thursday, August 14, 2008 3:37 PM
> To: Thomas Dietz
> Cc: Zseby, Tanja; Paul Aitken; psamp; Juergen Quittek
> Subject: RE: [PSAMP] PSAMP-INFO IE realtiveError
> 
> Hi Thomas
> 
> I don't think much has changed.  If I filter out the misunderstandings
> I think you get something like this:
> 
> Tanja:    What's this fixedError thing for?
> Paul:     It's the uncertainty of the measurement expressed as a fixed
>           amount of the measured units.
> Tanja:    That's a confusing name, let's call it absoluteError.
> Everyone: OK.
> Tanja:    Why do we even need relativeError then?
> Andrew:   I think it might be useful for certain measurement devices.
> Tanja:    OK, well keep it if you want.
> 
> 
> In conclusion, fixedError is now called absoluteError and we'll keep
> relativeError in case it's needed.
> 
> For those who followed the thread, does that sound fair?
> 
> 
> Cheers
> 
> Andrew
> 
> 
> On Thu, 2008-08-14 at 15:25 +0200, Thomas Dietz wrote:
> > Hi Tanja, Andrew, Paul,
> >
> > since the topic seems to be settled now can you please summarize
your
> > discussion in this thread? I would like to know what to put into an
> > updated version of the draft so that it can get published asap.
> >
> > Best Regards,
> >
> > Thomas
> >
> > --
> > Thomas Dietz                 E-mail: [e-mail]
> > NEC Europe Ltd.              Phone:  [phone]
> > NEC Laboratories Europe      Fax:    [phone]
> > Network Research Division
> > Kurfuersten-Anlage 36
> > 69115 Heidelberg, Germany    http://www.nw.neclab.eu
> >
> > NEC Europe Limited           Registered in England 2832014
> > Registered Office: NEC House, 1 Victoria Road, London W3 6BL
> >
> > > -----Original Message-----
> > > From: [e-mail] [mailto:[e-mail]] On
> > > Behalf Of Zseby, Tanja
> > > Sent: Donnerstag, 14. August 2008 15:03
> > > To: Andrew Johnson
> > > Cc: psamp; Juergen Quittek
> > > Subject: Re: [PSAMP] PSAMP-INFO IE realtiveError
> > >
> > > Hi Andrew,
> > >
> > > great. So it seems that after a lot of mice stepping on and off
the
> > > scale we have a common understanding of the terms :-) So to
> > > summarize:
> > > - we don't need an offset IE
> > > - we definitely include the absoluteError IE
> > > - we can also include the relativeError IE (maybe you as authors
> > > decide?)
> > >
> > > Kind regards
> > > Tanja
> > >
> > > > -----Original Message-----
> > > > From: [e-mail] [mailto:[e-mail]] On
> > > Behalf
> > > > Of Andrew Johnson
> > > > Sent: Thursday, August 14, 2008 12:13 AM
> > > > To: Zseby, Tanja
> > > > Cc: psamp; Juergen Quittek
> > > > Subject: Re: [PSAMP] PSAMP-INFO IE realtiveError
> > > >
> > > > Hi Tanja
> > > >
> > > >
> > > > On Sat, 2008-08-09 at 01:19 +0200, Zseby, Tanja wrote:
> > > > > Hi Andrew,
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: [e-mail] [mailto:[e-mail]]
> > > > > > On Behalf Of Andrew Johnson
> > > > > > Sent: Friday, August 08, 2008 8:48 PM
> > > > > > To: Zseby, Tanja
> > > > > > Cc: psamp; Juergen Quittek
> > > > > > Subject: Re: [PSAMP] PSAMP-INFO IE realtiveError
> > > > > >
> > > > > >
> > > > > > On Fri, 2008-08-08 at 18:07 +0200, Zseby, Tanja wrote:
> > > > > > > Hi Andrew,
> > > > > > >
> > > > > > > lets first forget about the fixed error and say we agree
> > > > > > > that
> > > we
> > > > > need
> > > > > > > something like an absolute error that defines the maximum
> > > > > > > error that can happen at each measurement (given the real
> > > > > > > error is
> > > > unknown).
> > > > > > > Then it was unclear for me why you report this together
> with
> > > > > > > a relative error which provides exactly the same
> information
> > > > > > > but only
> > > > > > as
> > > > > > > percentage of the measured value. It is only for
> convenience
> > > that
> > > > > > > we can report either format.
> > > > > > >
> > > > > > > relError=abserror/measured value
> > > > > > >
> > > > > > >
> > > > > > > e.g. you can e.g. say: The absolute error is +/- 0.2 kg:
> > > > > > > Person:   80.50kg +/- 0.2kg
> > > > > > > Mouse:     0.50 kg +/- 0.2kg
> > > > > > >
> > > > > > > That corresponds to the relative errors:
> > > > > > > Person:   0.249 %
> > > > > > > Mouse:   40%
> > > > > >
> > > > > > In the Accuracy Report Interpretation you only provide one
> > > accuracy
> > > > > for
> > > > > > the field, you don't report the accuracy per measurement.
> The
> > > idea
> > > > > > is to provide the margin of error for all measurements of a
> > > certain
> > > > type.
> > > > > >
> > > > > > The only use of the error field types that was originally
> > > intended
> > > > > > was in the Accuracy Report Interpretation, where the error
is
> > > > scoped
> > > > > > to
> > > > > the
> > > > > > field (and optionally template).  Unless you use a new
> > > > > > template
> > > per
> > > > > > record I'm not sure how you would scope the error value to
an
> > > > > > individual measurement.
> > > > >
> > > > > But this is absolutely in-line with the above. You can provide
> > > > > one absolute error for all timestamps or all byte measurements
> > > > > (or all weight measurements). With this you say what is the
> > > > > maximum error
> > > > when
> > > > > measuring the timestamp or bytes. This maximum error usually
> > > depends
> > > > > on the measurement method and therefore the absolute error (=
> > > > > the maximum possible error) is usually the same for all of the
> > > > > values measured with this method. I think this is exactly the
> > > > > same that
> > > you
> > > > > want to express, correct?
> > > >
> > > > Ah I see what you mean now.  In general I think that only one
> type
> > > > of error will be reported at once and that most of the time that
> > > > will be an absolute error.
> > > >
> > > > I think there is still value in providing a way to express a
> > > > relative error though.  For example, clocks tend to drift over
> > > > time so the larger the time measurement the larger the error,
> i.e.
> > > > accurate to within 1 second per day is 0.0011574%.
> > > >
> > > > Cheers
> > > >
> > > > Andrew
> > > >
> > > >
> > > > > >
> > > > > >
> > > > > > > Or you could say: The relative error is +/- 10 %. Then you
> > > > > > > get
> > > > the
> > > > > > > corresponding absolute errors:
> > > > > > > Person:   80.50kg +/- 8.05 kg
> > > > > > > Mouse:     0.50 kg +/ 0.05 kg
> > > > > > >
> > > > > > > If this is o.k., the second question would be:  do we need
> > > > > > > something like an offset/fixed error ?
> > > > > > > e.g. Offset: 0.25
> > > > > > > Person (real value):   80.50kg
> > > > > > > Person (measured):     80.75kg
> > > > > > >
> > > > > > > Mouse (real value):   0.50 kg
> > > > > > > Mouse (measured):     0.75 kg
> > > > > > >
> > > > > > > The only thing that might be confusing is if you have an
> > > > > > > offset and report it together with a relative error, since
> > > > > > > the
> > > relative
> > > > > > > error should still refer to the real value (without
> offset).
> > > But
> > > > > > > we
> > > > > > probably
> > > > > > > do not need the offset value.
> > > > > >
> > > > > > I don't think we have any need for an offset.
> > > > >
> > > > > o.k. I agree.
> > > > >
> > > > > >
> > > > > > > Hope this was not even more confusing...
> > > > > >
> > > > > > I think I understand how you may have misunderstood how the
> > > > > > error IEs were intended to be used.  I hope I'm making
things
> > > clearer...
> > > > > > perhaps the draft needs some clarification.
> > > > >
> > > > > I think we have the same understanding (see above). The
> > > absoluteError
> > > > > gives the maximum value from which a measured value can differ
> > > > > from the real value. The error is usually bound to the
> > > > > measurement
> > > method
> > > > > or system (i.e. the same for subsequent values).
> > > > >
> > > > > Kind regards,
> > > > > Tanja
> > > > >
> > > > > >
> > > > > > Cheers
> > > > > >
> > > > > > Andrew
> > > > > >
> > > > > >
> > > > > > > Kind regards
> > > > > > > Tanja (starting to see white mice)
> > > > > > >
> > > > > > >
> > > > > > > > -----Original Message-----
> > > > > > > > From: Andrew Johnson [mailto:[e-mail]]
> > > > > > > > Sent: Friday, August 08, 2008 5:14 PM
> > > > > > > > To: Zseby, Tanja
> > > > > > > > Cc: Paul Aitken; psamp; Juergen Quittek
> > > > > > > > Subject: Re: [PSAMP] PSAMP-INFO IE realtiveError
> > > > > > > >
> > > > > > > > [SNIP]
> > > > > > > > > > >> The intention was to say that the clock is 5
> > > > > > > > > > >> minutes slow,
> > > > > > > > > > >> +/-
> > > > > > > > 10
> > > > > > > > > > >> seconds - so there's both an absolute error and a
> > > > > > > > > > >> relative
> > > > > > > > error.
> > > > > > > > > > >>
> > > > > > > > > > >
> > > > > > > > > > > NOW I finally understand what you meant by
> > > > > > > > > > > fixedError initially
> > > > > > > > !!
> > > > > > > > > > > This I would not consider as error. Any fixed
> > > > > > > > > > > deviation
> > > I
> > > > > > > > > > > would
> > > > > > > > > > rather
> > > > > > > > > > > name "offset"...
> > > > > > > > > > > If it is known couldn't you add it to the value
and
> > > > report
> > > > > > the
> > > > > > > > > > correct
> > > > > > > > > > > time?
> > > > > > > > > >
> > > > > > > > > > In that case there would be no need to ever report
> > > > > > "absoluteError"
> > > > > > > > -
> > > > > > > > > > because all the original measurements can be
> corrected
> > > > > > > > > > before
> > > > > > > being
> > > > > > > > > > exported.
> > > > > > > > >
> > > > > > > > > Maybe for clarification:
> > > > > > > > > The absoluteError that I propose is different from
what
> > > > > > > > > you intended by fixedError. absoluteError is a maximum
> > > > > > > > > error
> > > that
> > > > > you
> > > > > > > > > would
> > > > > > > expect
> > > > > > > > > due to the inaccurate measurement (e.g. the timestamp
> > > > > > > > > may
> > > > vary
> > > > > by
> > > > > > > +/-
> > > > > > > > 5 ms).
> > > > > > > > > The real error that you make during measurements is
> > > > > > > > > unknown and can vary. Your fixedError is different. It
> > > > > > > > > is a fixed
> > > and
> > > > > > > > > known offset
> > > > > > > > for
> > > > > > > > > the measured values, correct?
> > > > > > > >
> > > > > > > > I think the absoluteError is the same as the originally
> > > > > fixedError.
> > > > > > > In
> > > > > > > > Paul's example above the fixedError was +/- 10 seconds.
> > > > > > > > I'm
> > > > not
> > > > > > > > sure how you would communicate the "5 minutes slow"
> part...
> > > > > > > >
> > > > > > > > The original idea was fixedError would say this is
> > > > > > > > accurate
> > > to
> > > > > > > > within
> > > > > > > X
> > > > > > > > units.  Both the fixed and the absolute error can be
used
> > > > > together,
> > > > > > > but
> > > > > > > > you just have to go with the least accurate one.  For
> > > example,
> > > > > > > > if
> > > > > > my
> > > > > > > > bathroom scales have a fixed error of 0.25kg and a
> > > > > > > > relative error
> > > > > > of
> > > > > > > > 0.5%, then they can weigh a person very accurate, but
are
> > > > > > > > rubbish for weighing mice:
> > > > > > > >   Person1:   81.50kg +/- 0.4kg
> > > > > > > >   Mouse1:     0.25kg +/ 0.25kg
> > > > > > > >
> > > > > > > > Cheers
> > > > > > > >
> > > > > > > > Andrew
> > > > > > >
> > > > >
> > > _______________________________________________
> > > PSAMP mailing list
> > > [e-mail]
> > > https://www.ietf.org/mailman/listinfo/psamp
_______________________________________________
PSAMP mailing list
[e-mail]
https://www.ietf.org/mailman/listinfo/psamp