Re: Unique identifiers & barcodes
Date: Sat, 24 Jul 1999 11:26:03 -0800
To: "James S. Ashe" <ashe@falcon.cc.ukans.edu>,
"Robert K. Colwell" <colwell@uconnvm.uconn.edu>
From: "John T. Longino" <longinoj@evergreen.edu>
Subject: Re: Unique identifiers & barcodes
Cc: John Pickering <pick@pick.uga.edu>, sackley@compuserve.com,
Steve Ashe <ksem@kuhub.cc.ukans.edu>, brianb@mizar.usc.edu,
Gladys_Cotter@usgs.gov, christine.deal@intermec.com,
faulzeitler@ascoll.org, mark_fornwall@usgs.gov,
David Furth <Furth.David@NMNH.SI.EDU>,
Winnie Hallwachs <whallwac@sas.upenn.edu>,
Dan Janzen <djanzen@sas.upenn.edu>,
"Norman F. Johnson" <Johnson.2@osu.edu>, mkaspari@ou.edu,
Jack Longino <longinoj@elwha.evergreen.edu>,
Scott Miller <scottm@bishop.bishop.hawaii.org>, becky_nichols@nps.gov,
Chuck_Parker@nps.gov, msharkey@byron.ca.uky.edu, ctemple@intermec.com,
cthompso@sel.barc.usda.gov, jugalde@inbio.ac.cr,
Piotr Naskrecki <pin93001@uconnvm.uconn.edu>, windsord@tivoli.si.edu,
dl@pick.uga.edu, "James S. Ashe" <ashe@falcon.cc.ukans.edu>
Hi all,
I just got Steve's message, and see that he covered some of the same
ground as the message I just sent. A few additional comments:
> Your comments about the accuracy of code 49 reads is interesting. A
>persistent "rumor" about barcodes that developed early in their use in
>entomology was that there were significant reading errors. I saw
>several demonstrations in which such reading errors occurred - all used
>code 49 barcodes. Upon reflection, I suspect that the problem was
>related to the relatively inexpensive barcode readers that were in use
>in those demonstrations - and were not directly the result of code 49
>itself.
My experience with code49 barcode reading is that it is prone to
error, in mysterious ways. A more knowledgable computer person could
probably explain this. I think it has to do with a wedge-computer
interaction. There have been times when the scanner acted drunk, and
misread the barcode every time. The errors were always in the form of
dropping out parts (I don't think I have ever seen a misread where it
switched a letter or number). In other words, the errors are all
deletions, not point mutations. And this would vary among software:
codes would read correctly into one application, but not into
another. I fixed this by changing a timing parameter in the wedge,
which slowed the rate at which data are transmitted to the computer.
Since then I have had no problem. One time in the ALAS lab, the
scanner suddenly got drunk, but rebooting the computer fixed it. I
suspect that this is not really a code49 problem, but rather a
general wedge interface problem.
But this sort of thing is rarely a serious problem. Most of the
individual barcode reading is to look up an existing specimen in the
database (for example, entering identifications), and if the specimen
code is not found you are beeped at. Most of our specimen codes are
entered automatically as long series, with only the first and last
code being scanned. So there are few opportunities for scanner
misreads to cause errors in specimen input.
Overall, in my experience, when the scanner is working properly,
misreads are very rare.
>Upon reflecting on these requirements, I believe that we must
>have a registry of such identifiers (with synonyms - for example, Jack
>mentioned that INBio has used both INBIOCR000000, and IB000000 - and if
>"SM" proves the be inadequate as an institutional identifier for the
>Snow Entomological Collection, then "SM" will need to be included as a
>synonym of whatever identifier is chosen).
INBio and ALAS have used only the INBIOCRI prefix on actual specimen
labels. The "IB" prefix was a "future Y2K" expedient used in our
database, now corrected so that the full prefix is used in the
database. The important thing in the registry will be actual specimen
codes that physically appear on a label. In the case of Snow, if it
changes to SEMC, the registry would list a series of specimens that
start with "SM," and another series that start with "SEMC."
Jack
******************************************************
John T. Longino
Lab I, The Evergreen State College
Olympia WA 98505 USA
longinoj@evergreen.edu
Ants of Costa Rica on the Web at http://www.evergreen.edu/ants
Project ALAS at http://viceroy.eeb.uconn.edu/ALAS/ALAS.html
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| Discover Life in America | Science | Unique Identifiers & Barcodes | Correspondence | John Longino - 24 July, 1999 |