ArcTools Exercise (Exercise 6) - University of Texas at Dallas



Project 1: Hypothesis Testing using ArcGIS or other GIS software

This exercise provides familiarity with using ArcMap, ArcCatalog, ArcToolbox and possibly Modelbuilder to test hypotheses. It provides experience with buffering, joins and map production.

• The objective of the research is to answer the question: Are disadvantaged groups (economic, racial or ethnic) more exposed to pollution than the non-disadvantaged?

Part 1: (due next week)

Here we examine all schools. Compare schools within 1 mile of a toxic site to schools beyond 1 mile. Calculate the proportion of students in each economic or racial or ethnic group for schools within one mile and for schools beyond one mile.

• Is there a higher proportion of economically disadvantaged or specific racial groups in schools within one mile (and thus potentially more exposed to pollution) compared to the proportion in schools beyond one mile? (Hint—calculate proportions relative to row sum). Use an Excel spreadsheet to examine this.

• On a map show:

o Toxic sites with a mile mile buffer around each

o All schools; use different color for schools within toxic site buffer

o Highways

Part 2: (due in two weeks)

Here we examine only schools within the buffer. For schools within one mile of a toxic site calculate an index of its exposure to toxic emissions.

• For all toxic sites within 1 mile of each school, divide the site’s toxic score by its distance to the school, then sum over the sites to create a “toxic index” for the school.

• Compare the demographic characteristics of the ten schools with highest toxic index (“TopTen” schools) to the demographic characteristics of all others within the one mile buffer

o Is there a higher proportion of economically disadvantaged or specific racial groups in the top ten schools (and thus potentially more exposed to pollution) compared to the proportion in other schools within the one mile buffer?

• On a map show:

o Toxic sites, schools and highways the same as last week

o for the top ten schools only, draw a symbol proportional to the school’s exposure index, and label with the school name

o Optionally: Clip or mask the data to show only Dallas County

o Optionally: produce a nice map layout, including tables and/or bar chart showing results. All printed maps should have North arrow, scale, datum/projection, data sources

Part 3: (due in three weeks)

Find and read two research papers published in academic journals which report on similar research To find these, use Google Scholar and/or Web of Science; search for Environmental AND Justice AND GIS or similar. Write a short paper comparing your methods and results with those used in these papers.

Big Challenge

1. Automate the analysis in Modelbuilder or Visual Basic for Application (VBA).

2. Apply the automated application to all schools in Texas or for other Metropolitan Statistical Areas (entire D/FW MSA, Houston MSA, San Antonio MSA, Austin MSA)

Data

Plan your approach first: in what order am I going to get data and how will I process it?

Implement using shapefiles, or using a File-based Personal Geodatabase (my preference).

For Part 2 you will need to use the POINT DISTANCE tool which is only available at the ArcInfo level under ArcToolbox>Analysis>Proximity It is not available at the ArcView level. Everything else can be done with ArcView.

• Dal_toxic_SPCS,shp contains the toxic sites and their toxicity scores

• Dal_schools_SPCS.shp contains the location of the schools

• Highways_NCTCOG_SPCS.shp contains major roads in the Dallas Fort Worth area

• County_NCTCOG.shp contains the county outlines for the counties in the Dallas/Fort Worth area

• Dal_sch_stats.dbf contains the number of economically disadvantaged (CPETECOC), African American (CPETBLAC), Hispanic (CPETHISC), Asian (CPETPACC), and White (CPETWHIC) in each school, as well as the total student body (CPETALLC). (Note: race groups may not sum to total student body; difference is “other races”.)

The coordinate system for all spatial data is:

NAD_1983_StatePlane_Texas_North_Central_FIPS_4202_Feet

North American Datum 1983

State Plane Coordinate System (SPCS), Texas North Central Zone

(Federal Information Processing Standard Code (FIPS) 4202)

Measurement units are feet. There are 5280 feet in one mile.

Extensive data for Dallas/Fort Worth (DFW) is available at



NCTCOG-North Central Texas Council of Governments is the planning agency region for the Dallas/Fort Worth area. Its boundaries differ slightly from those defined by the US Bureau of the Census for the Dallas Fort Worth MSA (Metropolitan Statistical Area). Both are based upon counties.

Environmental Hazard data is available at:

US Environmental Protection Agency (EPA tri sites)





tri—toxic release inventory

Texas Commission on Environmental Quality (TCEQ) data site



School data for Texas is available from the Texas Education Agency (TEA)





Other data (both human and natural) for all of Texas is available from the Texas Natural Resources Information System (TNRIS).



How to do it in ArcGIS : Part I

1. Bring in the data files (C:\Users\briggs\Documents\china\lectures\project-armap\data)

Dal_toxic_SPCS,shp contains the toxic sites and their toxicity scores

Dal_school_SPCS.shp contains the location of the schools

Highways_NCTCOG_SPCS.shp contains major roads in the Dallas Fort Worth area

County_NCTCOG.shp contains the county outlines for the counties in the Dallas/Fort Worth area

Dal_sch_stats.dbf contains the demographic statistics

2. For the demographic analysis, identify school within 1 mile of toxic sites

-- use Selection>Select by location to select all schools within distance of 1 mile (5280 feet) from Dal_toxic

--select features from Dal_school

--that “are within distance”

--Dal_toxic_SPCS

--add variable (e.g called buffer) to Dal_schools and code for inside(=1) and outside (=0)

--open attribute table for Dal_school

--click Options and Add Field (short integer) called Buffer

--right click column heading for buffer field (Dal_school_SPCS.buffer)

--select Field Calculator

--calculate Dal_school_SPCS.buffer = 1

--be sure there is a ( in Calculate selected records only

--Clear Selected Features after doing this (important!)

3. Obtain student count totals within and beyond buffer.

--Join Dal_school_SPCS layer with Dal_sch_stats table

--right click on Dal_school_SPCS and select Joins and Relates>Join

-- Box 1 ORG_NUM (for Dal_school_SPCS)

--Box 2 Dal_sch_stats

--Box 3 CAMPUS (for Dal_sch_stats in Box 2)

--open the attribute table for Dal_school_SPCS -be sure join is correct!

--click on heading for Dal_school_SPCS.buffer,select Summarize and Sum

the six Dal_sch_stats demographic fields (click expansion box, then check SUM)

--name the output table Sum_buffer: the output table should have two rows

--1= within buffer

--0= outside buffer

--it is saved as .dbf file which can be read by Excel

4. Use Excel to open Sum_buffer.dbf and calculate the percentages for within and beyond buffer

--you may need to close ArcMap

--you should calculate percentages relative to total within buffer and beyond buffer

--this is the row sum given by the variable Sum_CPETAL

Null Hypothesis: there will be the same percentage for each group beyond and within the buffer

Alternative hypotheses: there will be a higher percentage of Black, Low Income, Hispanic, and Asian students and a lower percentage of white students within the buffer.

|buffer | | |

|Count | | |

|Total | | |

|Black-AfAm | | |

|Low Income | | |

|Hispanic | | |

|Asian | | |

|White | | |

| | | |

|Beyond (0) | | |

|378 | | |

|270,742 | | |

|79,994 | | |

|143,326 | | |

|102,226 | | |

|10,304 | | |

|77,020 | | |

| | | |

|Within (1) | | |

|95 | | |

|61,750 | | |

|11,948 | | |

|38,428 | | |

|33,199 | | |

|2,328 | | |

|13,997 | | |

| | | |

| | | |

| | | |

| | | |

| | | |

| | | |

| | | |

| | | |

| | | |

| | | |

|Percentages relative to total within and total beyond (row sum) | | |

| | | |

|beyond | | |

| | | |

| | | |

|29.5 | | |

|52.9 | | |

|37.8 | | |

|3.8 | | |

|28.4 | | |

| | | |

|within | | |

| | | |

| | | |

|19.3 | | |

|62.2 | | |

|53.8 | | |

|3.8 | | |

|22.7 | | |

| | | |

|Supports hypothesis? | | |

| | | |

| | | |

|No | | |

|Yes | | |

|Yes | | |

|No | | |

|Yes | | |

| | | |

| |Count |Total |Black-AfAm |Low Income |Hispanic |Asian |

| |

|TopTen | | |28.8 |53.0 |37.8 |3.6 |

|Supports hypothesis? |yes |no |no |no |no |

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