Presentation

Geographic Information Systems
Stephen A. Matthews & Anne Vernez Moudon
Discussion Group Members
Tom Baranowski
Mark Daniel
Ann Forsyth
Kipling Gallion
Robin McKinnon
Joseph Sharkey
David Stinchcomb
Celeste Torio
“Context”
An overall goal should be …
To think creatively about how GIS and related
technologies can be used in food, physical activity,
and built environment research, and specifically to
stretch the technology and revise the methodologies
we currently use.
There are opportunities and challenges.
GIS Introduction/Background
GIS technologies/tools/data have existed since the
1960’s, and some of the spatial methods and data issues
have been known about since the early half of the 20th
century. We are in a much better ‘place’ doing GIS
research in 2007 than we were in 1987.
GIS remains a rapidly evolving field drawing on
new technologies for data collection, integration,
sharing, and analysis.
Importance of GIS - “Value Added”
1. New spatial data products and data collection technologies
(e.g., wearable GPS & other wireless sensors, high-resolution
air photos, etc.)
2. The integration of otherwise disparate data sets
(socioeconomic, business, crime, landuse, terrain, road
networks, traffic, health service, climate, etc.)
3. The ability to redefine conventional geographic units of
analysis (e.g. based on administrative neighborhoods) and
create new flexible geographies (e.g., egocentric
neighborhoods) to define context.
Importance of GIS - “Value Added”
4. Incorporating geographic relationships and structure in to
our models (e.g. through the ability to handle proximity,
distance, adjacency, and contiguity measures).
5. Flexibility in how scale can be incorporated in research.
Methodologically, scale affects how we can measure and/or
represent food/built environments.
6. Use and integration of exploratory spatial data analysis
techniques within projects
The Key Challenges / Issues
• Conceptual Models
• Conceptualizing Place (Neighborhood) “Beyond
the Census Tract”
• Tracking spatial behavior
– Where do people go?
• Data quality (standards) - validation issues
• Privacy/confidentiality issues
• Training related issues
#1: Conceptual Models
• Why built environment -> Obesity?
• What causal pathways?
Howard Frumkin (AJPM 2006) asked some key questions:
• What theoretical model should underlie our definition &
measurement of place?
• What characteristics of place should we measure?
• By what mechanism(s) does place affect outcomes of interest?
(How does the environment “get into people?”)
• How is human behavior and activity influenced by contextual
factors?
We should not be data driven?
#2: Conceptualizing Place
“Probably no other term is used so loosely or with
such changing content as the term neighborhood,
and very few concepts are more difficult to
define.”
“the concept of neighborhood has come down from
a distant past and therefore has connotations which
scarcely fit the facts when applied to a patch of life
in a modern large city”
Roderick McKenzie (1921)
American Journal of Sociology
pp. 344-345, and p. 346
Naïve Assumptions
In studies of the relationship between place and health
outcomes we tend to assume
place = neighborhood = census unit (tract)
and the primary census tract attribute of interest in the study of
health outcomes = SES.
But also …
• Places are bounded
• Places are isolated islands removed from larger
hierarchical and non-hierarchical contexts
• Places are typically defined at one ‘scale’
What
are the
boundaries?
How far does a
place extend?
How do we
capture the
dynamics
of place?
What
spatial scale is
most salient with
respect to outcomes?
#2: Conceptualizing Place
Challenging Conventional Wisdom?
Areal units are particularly sacred once they have
been established even though they later may
become serious obstacles to the solutions of
contemporary problems
Ron Abler, John Adams, & Peter Gould (1971)
Spatial Organization
What size is a neighborhood?
Despite Census Bureau portrayals of tracts as compact,
stable, neighborhood-like units and their reification* as
such by social scientists, population rather than territory
represents the decisive criterion in defining tracts.
* Investigators justify using the tract in terms of how closely it approximates a
‘real’ neighborhood.
But what do we know about tracts?
Substantial variation exists in the territorial size of census tracts
within and across metro areas.
Tract size for
Riverside-San Bernardino-Ontario
Metropolitan area
Median:
Mean:
Minimum:
4.9 km2 (1.9 mi2)
121.3 km2 (46.8 mi2)
0.5 km2 (.2 mi2)
Maximum: 20,700.4 km2 (7,992.5 mi2)
Calculations prepared for Lee, B.A. et al (manuscript under review) “Beyond the Census Tract”
Average interquartile range in tract size
2
25Intra-metropolitan
highest-density metro
areas:
1.1
to
6.2
km
variation also occurs in tract population
25 lowest-density metro areas: 2.5 to 27.8 km2
Average min/max tract size for 100 largest metro areas
45 of
the 100 largest
areas have tracts falling below and
Minimum:
.4 km2metropolitan
(.16 mi2)
above the prescribed 1,500-12,000
range.
2
Maximum: 1,319.0 km (509.3 mi2)
Median tract size is less than 2.6 km2 ( 1 square mile) in 22 of the top
100 metro areas but over 7.8 km2 (3 square miles) in 13 others.
23 metros have tracts of less than a square mile AND of more than 500
square miles.
Calculations prepared for Lee, B.A. et al (manuscript under review) “Beyond the Census Tract”
#3: Where do people go?
It is clear that we do not do a good job tracking spatial
behavior and this limits our understanding of where
people go (to shop, to exercise).
There is an established literature on the spatial patterns
or spatial dimensions of daily life. Studies of “Time”
geography date back to the 1960s and 1970s emerging
from the Lund School in Sweden and the pioneering
work of Hagerstrand).
Interest in time-space movement has been revitalized in
GIS environments based on the use of ‘geocodable’
activity diaries using GPS and wireless technologies.
#3: Where do people go?
Space-time aquarium with the space-time paths of African Americans, Hispanics and
Asian Americans in the subsample. Kwan 2000, p.197.
Kwan, M-P (2000) “Interactive geovisualization of activity travel
patterns using 3-D GIS” Transportation Research Part C 8, 185-203.
#3: Where do people go?
A close-up view
of downtown
Portland
Kwan 2000, p.
198.
Kwan, M-P (2000) “Interactive geovisualization of activity travel
patterns using 3-D GIS” Transportation Research Part C 8, 185-203.
Multiple Activity Spaces
Maps based on
geoethnography as
applied to the Three City
Project (Matthews,
various presentations and
Matthews et al, 2005)
Jane Jacobs (1961) The Death and Life of Great
American Cities claims that three levels of neighborhood
exist: the block, the community or district (of approx.
100,000), and the city as a whole
Ethnographic data Boston families (N=43,
)
998 locations
(removing all locations 20+ miles from respondent home)
Matthews (manuscript in prep.) The salience of neighborhoods
Academic Amnesia?
(H. Gans)
“Any city dweller can test for himself the
meaning of his place of local residence. If
he will list his major activities and then
spot their focal centers on a map he will
quickly discover that his associations and
his associates are rarely to be found in the
immediate vicinity of his home. Nor will
he ordinarily find the home of his best
friend in his neighborhood.”
-- Barbara McClenahan
Sociology & Social Research (1946, p. 272-3)
Map : Matthews (manuscript in prep.)
The salience of neighborhoods
(John Everitt (1976) cites similar comments by McClenahan on use of non-local communities in 1926)
#4: GIS Data Quality/Standards
Without accurate, comprehensive, and timely data to work
with researchers fall quickly (maybe unknowingly) into the
“garbage in, garbage out”
(GIGO) trap
No form of presentation or analysis (descriptive or
sophisticated modeling) can hide the limitations of the data.
Some of the ‘limitations’ may be unknown due to a lack of
metadata and/or ‘standards.’
#4: GIS Data Quality/Standards
Metadata: The good news is that the US has a Federal
Geographic Data Committee (FGDC) and back in 1993 they
outlined a concept for a National Spatial Data Infrastructure.
In part this need arises because digital data are often incomplete
and/or incompatible, but the user may not know this because
many datasets are poorly documented. The lack of metadata
inhibits the ability to find and use data, and hinders data
sharing between users.
Issues can be especially relevant for “spatial” databases include:
accuracy/precision
boundary issues
coverage
timeliness/timeframe alignment
scale / resolution
#4: GIS Data Quality/Standards
There are many groups involved in GIS standards.
A key organization is the Open Geospatial
Consortium (OGC) which focuses on interoperability
standards but much of the work of the Federal
government is unfinished.
Some of these issues of standards and maintaining
metadata on GIS data overlaps with training (for GIS
technicians and changing the culture regarding
documentation).
#4: GIS Data Quality/Standards
National Database of Community Indicators
Although researchers such as Coulton (1997) have called
for the creation of national databases that contain
community-level indicators this is still not feasible as data
sources and availability differ at all geographic scales.
In single or small number of site studies it is easier to
construct detailed databases.
Sample reports – need to
check to see if updates exist
Neighborhood Indicators:
Taking Advantage of the New
Potential
by G. Thomas Kingsley.
Working Paper. Chicago, IL:
American Planning
Association, October 1998.
Catalog of
Administrative
Data Sources
Claudia J.
Coulton with
Lisa Nelson and
Peter Tatian, in
Mapping Your Community:
Using Geographic
Information to Strengthen
Community Initiatives, by G.
Thomas Kingsley, Claudia J.
Coulton, Michael Barndt,
David S. Sawicki, and Peter
Tatian. Washington, D.C.:
U.S. Department of Housing
and Urban Development,
October 1997.
#5: Privacy/ Confidentiality Issues
• We need to understand when privacy is an
issue.
• Understand how data are handled in a GIS and
what we can and cannot map/publish.
• Understand the implications for data sharing.
• Need for journal reporting standards.
Marc Armstrong (2002) “Geographic Information Technologies
and their potentially Erosion Effects on Personal Privacy” Studies in
the Social Sciences, 27 (1): 19-28.
Locations of 30 randomly selected addresses in Iowa City
19 = Exact inverse address matched (63%) 63%
6 = Within one address (20%)
83%
4 = On the correct street segment (14%)
97%
“This level of local accuracy means that there is significant
risk that individual-level dot mapped information can be
compromised to reveal addresses, and by implication,
personal identities.” (p. 23)
#6: GIS Training
We recognized a need for GIS training researchers
(project managers) and for GIS technicians
- Culture of Documentation
- Skill needs in research methods, basic statistics,
computer science/basic database skills, visualization.
We saw a need to building capacity in GIS at
institutions independent of specific projects. Trained
experts rather than learning as you go.
#6: GIS Training
University Sector
Despite the facts that there are approximately 70 U.S. academic
institutions that are fee-paying members of the University
Consortium for Geographic Information Science (UCGIS), that
the number of GIS-related courses at the undergraduate and
graduate level is growing, that the number of on-line GIS
certificate and Masters programs has grown, and that model GIS
curricula have been developed (by UCGIS in 2006), the actual
number of formal training programs offering courses on GIS and
spatial analysis that are tailored towards health and social science
applications are very few.
#6: GIS Training
Vendors
The leading GIS/spatial analysis companies do offer regular
workshops and even online resources based on their products
(see for example ESRI (ArcGIS vendor) http://training.esri.com).
These vendor courses vary widely in content, focus primarily on
the product rather than necessarily the application, cover
applications that are frequently tailored to the commercial use of
the software, and also of importance to our target audience are
not priced for the education market and can retail at around
$500/day. Moreover, vendor training opportunities are rarely
targeted towards health and social science research questions and
applications.
GIS Breakout Group
Recommendations
1. Not GIS per se but we need more conceptual
development and theoretical models on the mechanisms
linking people and places.
2. Social and health science research is already seeing the
emergence of studies where data on individuals embedded in
multiple (and non-nested) geographically defined contexts are
being collected and integrated. GIS and related technologies
will play a key role in managing, visualizing and
analyzing these kinds of data. We need to think more
critically about definitions of neighborhood and measures of
the characteristics of neighborhoods. We can use GIS to
create person-centered neighborhoods (distance and spacetime buffers).
GIS Recommendations (cont.)
3. In future studies we can expect that space and time will
be increasingly partitioned into smaller collection or analytical
units. We already see projects that include the space-time
tracking of individuals 24/7 these technologies and research
designs will permit better understandings of spatial behavior and
in theory permit the use of GIS to contribute to the
development of measures of exposure to our defined
neighborhoods.
4. Collecting data on spatial behavior will permit researchers to
focus on the utilization of specific stores, parks, etc. rather than
assume an impact based solely on accessibility/proximity.
Moreover, such data will help researchers better understand
frequency, duration, and sequencing of food/exercise activities in
relation to other activities (and integration of social networks and
locations).
GIS Recommendations (cont.)
5. Social/health scientists will increasingly try to measure/capture
‘neighborhood’ (and the built and social contexts of individuals)
via secondary data sets. Typically these secondary data sets are
not collected for the purposes of facilitating health and social
science research and there is a need to validate these databases. GIS
will have a role to play in these studies, above and beyond
concerns over positional accuracy. We need more of this type
of fundamental research across diverse contexts.
6. With more detailed spatial data now available on individuals and
with the ease of integration of these data with other contextual
databases the need for expertise in handling confidentiality and
privacy issues will be real.
GIS Recommendations (cont.)
7. Unlike the social environment and physical environment there
are few national standardized measures of the built environment.
We need to find government (and private sector partners ?) to help
promote this kind of data as a resource. (many issues of
maintenance and currency of the data remain).
8. GIS training opportunities are out there but difficult to find,
and few are tailored to current research needs.
9. The largest GIS cost is personnel time (not data, hardware, or
software). GIS support personnel and infrastructure between and
within college campuses varies enormously. Need to build
capacity and teams that can facilitate research using GIS data and
spatial analysis methods.
GIS Recommendations (cont.)
10. This group should probably try to develop (based on existing
materials from GIS and other fields) guidelines vis-à-vis the
minimum standards acceptable for the use of specific data sets and
guidelines for a minimum checklist of items that ought to be
reported to the ‘reader’ in submissions to journals as well as similar
lists of GIS-related methodological or data issues to be addressed in
crafting grant proposals.