11.520: A Workshop on Geographic Information Systems |
11.188: Urban Planning and Social Science Laboratory |
INTRODUCTION
In this exercise, you will explore the spatial patterns of the housing and
socio-economic characteristics of communities in and around
We ask you to use these data to prepare a short report with textual discussion plus three maps for Part I and two maps (with a table) for Part II.
Before starting the hands-on work, read through the entire assignment to get a sense of the datasets, analytic approach, and processing steps. Then, make sure you can access the datasets in the 11.520 Locker. [As explained in the lab exercises, you can find the locker by navigating through the sub-directories on network drive Z:, or you can attach the class locker to a new drive letter - we suggest Drive M: (for maps). The earlier lab exercises explained how to mount the Andrew File System locker //afs/athena.mit.edu/course/11/11.520/ on network drive M:]
DATA
The census tract boundaries are saved in a 'shapefile' that contains only the boundary geometry and a few geographic identifiers (like county, track number, etc.). This shapefile must be joined with a dbf-formatted table in order to relate the census data to specific census tracts. The census tract shapefile is called msa5_tr90.shp. It is located in the class data locker (M:\data) and contains all the 1990 census tracts in the five Eastern Mass counties in and around Boston.
The socioeconomic data for these tracts have been pulled from the 1990 Census SF3A datasets and are stored in the same M:\data directory in a dbf-formatted table called msa5_tr90_data.dbf. This file must be 'linked' or 'joined' to the attribiute table for the tract boundaries by a common field called "STCNTYTR" before you will be able to generate thematic maps using the census data. (STCNTYTR is the abbreviation for STate-CouNTY-TRact.) Use the ArcMap help files to see how to 'join' the data table to the attribute table if you want to get started with the homework before we show you how to do this in class.
The msa5_tr90_data.dbf table includes 60+ variables from the much longer list of all variables in the decennial Census. Take a look at the dictionary for the specific census data fields in msa5_tr90_data.dbf. (Note: this list is a subset of the full Census Bureau's listing and technical documentation for the hundreds of population and housing variables from the 1990 census. This technical document is archived in the class locker as M:\data\census90\census90stf3td.pdf. More details about the 1990 US Census are available in Tom Grayson's and Annie Thompson's notes on "Making Sense of the Census". Be aware, however, that some of the online references in these notes are no longer available and you will need ONLY the shorter list of 60+ variables mentioned above in order to do the homework. During the next few weeks we will have additional exercises using US census data, but we will use the 2000 US census for those exercises and will provide the relevant technical documentation. Also, note that small-area comparison of census data across decades can be tricky due to changes in census tract and block group boundaries. MIT's Rotch Library has CDs from a third-party firm, GeoLytics, which has reconciled past census data to year 2000 boundaries. Should you wish to analyze trends in census data for your individual project later in the semester, you will likely want to use the GeoLytics CD.)
Besides the census data, which will be used primarily in Problem #1, you will need a map of major roads and shopping centers for Problem #2. The shopping center coverage (for the Boston metro area) is called shopcntrs and is also stored in M:\data. The major roads layer is called majmhda1 and can be also found in the directory M:\data. All of these coverages use the following coordinate system: Massachusetts State Plane, Mainland Zone, NAD 1983, meters. **Be sure to set the map units and distance units in the Data Frame Properties window so you can measure distances in your Data View window and be sure that the distances you compute in Problem #2 are reasonable.**
Data Sources: The roads coverage comes from the Mass Highway Department via MassGIS and the shopping center coverage is proprietary data provided by SSR Research (circa 1995) for internal MIT educational use.
SUMMARY
A map should always have a purpose. A good map should deliver the information that you want readers to understand. Therefore the map should be very intuitive without requiring reading the discussion of the map in your paper or report. Try to give the map to your friends who have no training in GIS to see if they can recognize the message you were trying to deliver and ask them whether they find the evidence to be compelling.
1. [20 points] Create a thematic (or chloropleth) map showing the population density of the MSA.
2. [20 points] Map the homeownership ratio--the ratio of owner occupied housing units to the total occupied housing units.
3. [20 points] Map another Census attribute of your choosing with interesting spatial patterns using the same process as described in number two.
For this problem, you are asked to investigate the relationships among the locations of shopping centers, major roads, and residential clusters. After doing some exploratory mapping as you did in the first problem, you are asked to dig a bit further into the data, develop a few specific measures that carefully exclude incomplete or inapplicable data, and then develop maps that successfully visualize the results and the reasoning behind your analysis.
The shopping center data are stored in a shapefile at M:\data\shopcntrs.shp. (These data are proprietary and not to be used or redistributed for non-MIT purposes.) Included in these data are characteristics such as square footage of retail space (totalsf as a text field and squarefeet as a numeric integer) and type of center (propertysu).
Explore these two variables to try to determine if a relationship exists between them. To do this you may want to calculate the average size of each type of shopping center. Note that not all observations include a value in the totalsf or squarefeet fields. Note that these shopping 'centers' do not include places like Central Square (Cambridge) where commercial/retail activity is present among individually owned parcels and buildings along a city street. This dataset focuses on shopping center developments where a large tract of land or strip mall under common ownership is divided up into clusters of businesses.
1. [20 Points] Create one map showing the relationship(s) between shopping center location and the location of major roads and population centers.
2. [20 Points] Buffer the major roads and create a second map that examines whether certain types of shopping centers tend to be inside the buffer.
Explain in a couple of paragraphs, separate from the maps, (a) the steps you took to select those roads and shopping centers that you included when computing your statistics, and (b) your interpretation of any general pattern that you observe regarding the location of shopping centers, major roads, and population centers. In particular, be sure that your discussion covers:
- What conceptual relationships are these maps intended to portray?
- Which classification schemes did you choose to use, and why?
- Which shopping centers and tracts have you excluded from the analysis, and why?
- Do there appear to be any interesting spatial relationships shown on the map?
Homework Requirement
Don't just turn in the maps! You should turn in a short report that integrates the maps and tables together with the explicit answers to both questions. Use the maps and tables in the paper to illustrate and amplify your verbal reasoning rather than simply to produce maps without a stated context and purpose.
Please submit your homework (in WORD, RTF and/or PDF format) using the Stellar homework turn-in capability at http://stellar.mit.edu/S/course/11/fa10/11.520 or http://stellar.mit.edu/S/course/11/fa10/11.188
by 2 PM Wednesday, October 13, 2010.
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