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| Subject: | GISList: Re: 80% of data having spatial reference? |
| Date: |
12/23/2001 09:22:53 PM |
| From: |
Duane F. Marble |
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A while ago there was some discussion of a possible reference regarding
the "80% of data having spatial reference?" topic. Since Rebecca Sommers
was mentioned, I passed copies of the messages along to her (former
student of mine). Recently she replied as follows:
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Thanks for the information about the search for the source of the 80% rule.
I'm sorry it took me a while to respond. I wanted to find and review the
Chorley report. I also wanted to find another report that was done around
that time that quoted a bunch of North American GIS statistics resulting from
a study group that did a tour including Calgary. I thought it was something
like the Nordic Report. I hope it is not a figment of my imagination or that
I have confused it with the Chorley investigative teams.
But it doesn't really matter because I don't think anybody was quoting
anybody else's report or publications. It seems more like they were just
repeating the same folklore. This is what I know about the 80% rule:
* 70-80% is mentioned in Chorley (page 45) in reference to the Burnaby
system-probably quoting Harry Christie. I don't know if Harry actually
measured this phenomenon. I think it is more likely that he was quoting the
same folklore. But I don't know if it is mentioned elsewhere in the report.
I skimmed through, but I was tired.
* I mentioned 70- 80% in my 1987 PERS paper, but I know I was quoting
folklore. I had not yet seen Chorley.
* I think the folklore may have its origin in URISA. I can't remember who
all I heard quote 80%, but it was fairly common in the early 80s. The only
person I specifically remember saying it was Steve Kinzy from HDR. But I
suspect it might be found in some URISA papers around that time. (I have a
lot of the earlier proceedings in the garage but I am not likely to look at
them until Spring, if ever.)
So I don't know if this helps the guys trying to hunt it down. I also would
like to see it really measured and documented somewhere, so if anyone figures
this out, I would appreciate the reference.
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Unless somebody can find a real citation, I guess this gets filed in the
GIS "urban folklore" category!
--
Dr. Duane F. Marble
Professor Emeritus of Geography Telephone: 614-292-4419
Center for Mapping Fax: 614-292-8062
The Ohio State University
1216 Kinnear Email: marble.1@osu.edu
Columbus, Ohio 43212
"Two important characteristics of maps should be noticed.
A map is not the territory it represents, but, if correct,
it has a similar structure to the territory, which accounts
for its usefulness. . . . " (pg. 58)
- Alfred Korbzybski in Science and Sanity, (1933, 1950)
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