[Taxacom] Data quality of aggregated datasets

Karl Magnacca kmagnacca at wesleyan.edu
Thu May 9 03:01:38 CDT 2013


> You should *always* capture the radius -- even for GPS coordinates.
> You cannot know in advance what the information will be useful for,
> and not all GPS devices record with the same accuracy.  A GPS with
> +/- 100m may be no different from one with +/- 10m if you are doing
> ecological analysis; but it could make a huge difference if your
> goal is to return to the same tree or coral head or whatever.  I
> think it's just silly to throw away information when it's easy to
> capture.  It's also silly to think you know in advance what
> information will, or will not, be useful to future researchers.

The problem is that the supposed accuracy reported by the instrument
seems to have little relation to the actual value, whatever it is. 
As you said, it's cryptic - I've had a unit record points that seem
to be repeatably correct within <3m while reporting an error radius
of 15m (though that could be an example of false precision from
using the same unit), and just yesterday it was telling me the
accuracy was 7m while simultaneously shifting over 50m as I was
standing still.

Also, since it's not recorded by the unit (at least any that I've
used) and changes by the second, recording it requires taking it
down in a notebook and maintaining it partly separate in a file. 
Not a huge burden, but when it's of dubious quality, it hardly seems
worth it.

Karl





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