[Taxacom] Data quality of aggregated datasets

Stephen Thorpe stephen_thorpe at yahoo.co.nz
Tue May 7 01:36:01 CDT 2013


Yes, there is a tendency for biologists to use too many decimal places. Suppose you collect a specimen of a flying insect. How far could it range in 1 day?? Quite far, I think! How did it get to where you found it? Did it travel on you unnoticed for a while and then hop off, only to be captured? Who knows? There is actually no problem with giving an (overly) precise georef. The problem is with interpretation. What does a map of such points plotted mean? It depends on a lot of things. The more points the better, to see the broad patterns. Is it a species of high or low dispersal ability? Does it venture into synanthropic habitats? All these factors can make a difference. Collection localities have fuzzy boundaries. They are not simply "points". Rather they are areas radiating out from a point with ever decreasing probability the further away from the point. But nevermind, let's just get on with it ...
 
Stephen

From: Robert Mesibov <mesibov at southcom.com.au>
To: dyanega at ucr.edu 
Cc: TAXACOM <taxacom at mailman.nhm.ku.edu> 
Sent: Tuesday, 7 May 2013 5:56 PM
Subject: Re: [Taxacom] Data quality of aggregated datasets


Doug Yanega wrote:

"That means that legacy material being georeferenced NOW is almost all being given coordinates based on a resource like Google Earth, /which uses WGS 84/."

Collectors are using Google Earth more and more to georeference their sites. Expect to see lots of published or databased lat/lon data like
22°06'57.54"S
117°53'15.31"E,
with one-hundredth-of-a-second accuracy, because that's the default for cursor position in Google Earth. In my part of the world, that's about +/- 15 cm on the ground.

I've just checked, and the Australian Bureau of Meteorology says the current temperature in Melbourne, which sprawls over ca 9000 sq. km, is 18.7 C.

It's the triumph of the 'The More Numbers, The More Scientific' school of thought. I'm glad I've lived to see it. For the curious, I'm 24532.376 days old.
-- 
Dr Robert Mesibov
Honorary Research Associate
Queen Victoria Museum and Art Gallery, and
School of Agricultural Science, University of Tasmania
Home contact: PO Box 101, Penguin, Tasmania, Australia 7316
Ph: (03) 64371195; 61 3 64371195

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