Monday, September 20, 2004

UP 507 Advanced Geographic Information Systems (Winter, 2001)

English Home/ UP507 Course Home/ UP835 UTEP Research Seminar/ Resume

Empowerment Zone (Locator / Urban EZ/ECs)

# UP 507 Information Systems Course Project

Introduction

## Project I : Designating control areas in geographical space

### Research Question

What is a good procedure for measuring similarity and dissimilarity of socioeconomic characteristics between geographical units such as census tracts?
How can GIS contribute to managing the values representing socioeconomic characteristics in space as a tool to find control areas?

### Research Scenario

Select variables which represent socioeconomic characteristics for each census tract in the Detroit Metropolitan Area.  I considered 25 variables.
Execute factor analysis to get factor scores for each census tract.  From the factor analysis, reduce the number of variables to several factors, each of which represents some socioeconomic characteristics such as income or poverty.  Compute factor scores for each census tract.  I extracted three types of factor scores for each census tract.

Draw a thematic map of the Detroit Metropolitan Area with factor scores by census tract.

Designate a control area that falls into the same class as the DEZ.

Pursue a statistical hypothesis test to verify whether or not the experimental area (DEZ) and the control area are the same in terms of the socioeconomic characteristics that are represented by factor scores.Iterate the process from the thematic map stage until getting a suitable control area.

### Method (using Detroit Empowerment Zone)

 Hypothesis Test Step I Step II Step III Step IV T-test Overview

## Project II : Areal Interpolation

### Research Question

Suppose two areal units with different boundaries in geographical space; one is the area that does not have necessary data, and the other is the area that has the data.  Let us call the former the target zone and the latter the source zone.
In the case that the source zone area contains the target zone area, can we get the data for the target zone from the source zone using GIS?

### Research Scenario

Data needed
We need annual employment and business establishment data by census tract of Detroit Empowerment Zone (DEZ).
Identification of a target zone
DEZ is made up of 48 census tracts, but the tracts do not have annual employment and establishment data.
Identification of a source zone
The zip code business patterns has annual employment and establishment data by zip code.
The areal interpolation method using GIS can provide us with these statistical data by overlaying the DEZ map on the zip code boundary map with the data.

### Method

General Information
Location of DEZ (Map 1)
DEZ is made up of 48 census tracts, which do not have annual employment and establishment data (Map 2).  Let us call DEZ the target zone which means that it does not have needed data.

The zip code map containing DEZ with annual employment and establishment data by zip code is made up of 17 zip code areas (Map 3).  Let us call it the source zone which means that it has needed data.

Process of Areal Interpolation
(STEP I : Digitizing)
Superimpose the target zone map (DEZ map) on the source zone map (Zip code map) (Map 3).
Split the source zone layer by the census tract lines of the target zone (Map 4).  110 polygons with the annual employment and establishment data were made (Map 5).  Note that there is no unique key field in the attribute table.  Without a unique key field, we cannot perform a spatial join to create a new attribute table by linking attribute tables of multiple layers.  For the spatial join, each attribute table of the layers should have a common unique key field.
(STEP II : Union)
Superimpose the target zone map (DEZ map) on the source zone map split by DEZ census tract lines with 110 polygons (Map 6).
Execute union of the polygons into DEZ census tract.  Then, we can get a map with 48 polygons which are exactly consistent with DEZ (Map 7).  Note that the attribute table has annual employment and establishment data, but still does not have a unique key field.
(STEP III : Linking the polygons to data tables)
What we need is a data table with both annual employment/establishment and socioeconomic data by census tract.
First, link the table with socioeconomic data by census tract (Table 1) to the DEZ map by census tract (Map 2).  Then, we can get the DEZ map with socioeconomic data by census tract (Map 8)

Second, we want to perform a spatial join of Map 8 to Map 7 to create a new census tract layer with both socioeconomic data in Map 8 and employment data in Map 7.   However, the maps do not have a common key field to join with.  For this, create a key field named ID in the attribute table of  Map 7 (Map 9).  Seek POLID, which means Polygon ID, of each polygon in Map 8 to make a data table (Table 2) which matches ID's in Map 9 with POLID's in Map 8 (Map 10).  Join Table 2 to the attribute table of Map 7 with ID field as common key field to create the map which has the employment and establishment data table with POLID field as unique key field (Map 11).

Finally,  join Map 11 to Map 8 with POLID field.  Then, we can get the DEZ map (Map 12) with its attribute table containing both employment/establishment and socioeconomic data by census tract (Table 3).

 General Information Map 1 Location of Detroit Employment Map 2 Detroit Empowerment Zone by 1990 Census Tract (With POLID) Map 3 Zip Code Area Containing DEZ Table 1 Socioeconomic Data by 1990 Census Tract in DEZ STEP I: Digitizing Map 4 Split Zip Code Layer by DEZ Census Tract Lines Map 5 Zip Code Map After Split by DEZ Census Tract Lines STEP II: Union Map 6 Union of Split Polygons by DEZ Census Tract (Before Union: 110 polygons) Map 7 Union of Split Polygons by DEZ Census Tract (After Union: 48 polygons with employment data consistent with DEZ) STEP III: Linking Polygons to Data Tables Map 8 Detroit Empowerment Zone by 1990 Census Tract (With POLID and socioeconomic data) Map 9 Detroit Empowerment Zone by 1990 Census Tract (With a new ID field and employment data) Map 10 Table 2 Map 11 Detroit Empowerment Zone by 1990 Census Tract (With POLID and employment data) Map 12 Detroit Empowerment Zone by 1990 Census Tract (With employment and socioeconomic data) Table 3 Employment/Establishment and Socioeconomic Conditions by 1990 Census Tract in Detroit Empowerment Zone

### Assumption

Areal interpolation is based on the assumption that employment and business establishment are evenly distributed throughout every zip code area.  This assumption, resulting in probable inaccuracy in the actual number of employment/establishments, functions as a limitation in collecting data using the areal interpolation method when we use the actual numbers for a study.
However, this assumption can be tolerable if the data are used for comparing changes over time in an area since we can assume that the annual % change of employment/establishment in a same area over time is not different.