[DDI-ADG] UNC document

[Mary Vardigan]

Wendy and others,

This sounds right to me. I think I will get in touch with John again to
ask about the machine-actionability issue.

Mary

-----Original Message-----
From: ddi-adg-bounces at icpsr.umich.edu
[mailto:ddi-adg-bounces at icpsr.umich.edu] On Behalf Of Wendy Thomas
Sent: Tuesday, November 08, 2005 4:57 PM
To: ddi-adg at icpsr.umich.edu
Subject: [DDI-ADG] UNC document

After reading this through it does seem like the vast majority of the
information items noted are in the collection methodology section. After
looking at the work that was done by the various working groups and the
content of DDI version 2.0, the SRG concluded that significant work
needed
to be done on the structure of items currently in section 2 of the DDI
(study description and methodology). The need for improvement in these
sections touches on all types of data and should be conceptualized and
approached in a unified way. For that reason, major restructuring of
this
section (aside from the instrumentation piece) will be scheduled for
3.x.

In fact, it looks like a lot of what they want is already in the DDI but
only as PCDATA buckets. It would be interesting to note what special
needs
they have in each area and whether those need to be machine-actionable
or
just captured.

That said, the spacial data requirements here are not that complex and
many are not unique to geographic based collection. We have addressed
many
of the temporal pieces and the availability of reusable classes on
agents
and roles should address some additional points.

The main geographic items are:

1) identifying the type of geography expressed by an observation (point,
line, or polygon)
2) uniquely identifying that within the observation
3) linking it to an appropriate geographic boundary file (if required)

To address each in turn:

1) refer to FGDC/ISO to obtain a controlled vocabulary list of
geographic
types (there is also circle and arc that I know of) and provide an
element
that allows identification of the most descrete geographic type

2) This can currently be done. A variable (or 2 variables) can be used
to
identify the long/lat of a point thereby identifying it uniquely. A line
is simply a start and end point. A polygon is commonly linked to a
geographic file by its identifier (code or name). If you have unique
polygones such as self determined plots, it is best to describe the
polygon using a geography based system (FGDC/ISO etc) providing a unique
identifer to each polygon and then using that identify in the data
record
as a link.

3) see 2

or am I missing something in this?

wendy

Wendy L. Thomas                          Phone: +1 612.624.4389
Data Access Core Director		 Fax:   +1 612.626.8375
Minnesota Population Center              Email: wlt at pop.umn.edu
University of Minnesota
50 Willey Hall
225 19th Avenue South
Minneapolis, MN 55455

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