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<div class="moz-cite-prefix">On 1/11/22 1:10 PM, Cassidy, Kelly
Michela wrote:<br>
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<p class="MsoNormal">Ha ha, that’s the type of location
description that makes me want to throw random (virtual) darts
at a map, because it would probably be as accurate as the
description. I don’t think you have a GeoLocate or Google
Earth problem; you have a collector who was probably either
guessing how many road miles he’d traveled or guessing at
which county he was in. All you can do is decide whether you
want to put the point 17 miles out in a different county or
put it in the right county, but less than 17 miles down the
road. Either way, the “Uncertainty” field gets a big number. <o:p>
</o:p></p>
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<p>Quite the opposite.</p>
<p>This collector was scrupulous in reading his trip odometer, and
scrupulous about resetting the trip odometer whenever he left a
town. Carrizozo is a town less than a mile from end to end. I
assume that the resulting georeference is accurate to within a
mile, accordingly (a half a mile error for the odometer, and at
most a half a mile for the edge of the town).</p>
<p>The uncertainty radius on most such labels is typically databased
as 2 km, sometimes much less (e.g., "vic. Big Dune, 4.3 mi W jct
Hwy 95 & 373" is accurate to within a few hundred meters).
Many landmark features are small, and stable over very long time
frames, if they are not associated with large sprawling urban
areas. A label saying 17 mi W Carrizozo is <b>very</b> precise; a
label saying 17 mi W Albuquerque is nearly useless. Entomologists
in pre-GPS days (but after 1930 or so) often reported their
odometer readings to the nearest 1/10 mile, and/or also gave
elevation from altimeter readings. It is not at all a difficult
thing to recreate a person's trip when you know that the way
entomologists collect is to drive around, stop the car at the side
of the road, collect nearby, and then get back in the car and go
on to another stop. It's a <b>very</b> rare thing for a
collecting locality to be somewhere from which one's parked car
would not be visible. In fact, the error radius associated with
how far a person might have wandered on foot from their parked car
is probably nearly the same as the error associated with
determining where they had to have been parked.</p>
<p>Also, in those few circumstances where we DO have additional
evidence to use as a check (field notes, records from more than
one collector at the same site, direct questioning of collectors,
etc.), the precision and accuracy of post-facto georeferencing <b>along
roads</b> has proven to be pretty solid on the whole; I can't
think of a single such case where the actual spot was not inside
the error radius we'd assigned. That being said, labels made prior
to the routine use of odometers are generally hopeless, as are
labels that only give the names of cities or towns, or irregular
or linear features like a lake, river, mountain, or canyon. THOSE
records usually have a very large associated error radius.
Conversely, there are a fair number of collectors who write down
incorrect GPS values on their labels, or mis-transcribe things so
you get nonsense entries like "33° 78.56" N", so even the access
to technology doesn't prevent careless mistakes that require
careful georeferencing.</p>
<p>Peace,<br>
</p>
<pre class="moz-signature" cols="72">--
Doug Yanega Dept. of Entomology Entomology Research Museum
Univ. of California, Riverside, CA 92521-0314 skype: dyanega
phone: (951) 827-4315 (disclaimer: opinions are mine, not UCR's)
<a class="moz-txt-link-freetext" href="https://faculty.ucr.edu/~heraty/yanega.html">https://faculty.ucr.edu/~heraty/yanega.html</a>
"There are some enterprises in which a careful disorderliness
is the true method" - Herman Melville, Moby Dick, Chap. 82</pre>
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