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Equity Atlas Data Description
Geographies Background:
Census Tract populations range from 1,200 to 8,000, have an average population of 4,000, and are intended to be relatively homogeneous units with respect to the resident population’s characteristics, economic status, and housing conditions. There are 375 Census Tracts completely within Bexar County. Census Tracts do not follow the CoSA boundary. Both Decennial Census and ACS Tract level data are available for Bexar County.
Blocks are the smallest subdivisions of Tracts. They are typically bounded by visible features like roads and boundaries like city limits. They can have populations that vary from zero to several hundred, such as when an apartment complex occupies the entire area. Blocks are the smallest geographic unit used by the Census Bureau for tabulation of 100-percent data (Data collected from all houses such as in the Decennial Census). There are 23,698 Blocks in Bexar County, 18,629 of which had a population of at least one and as much as 5,052 in the 2020 Decennial Census.
Demographic Data Background:
The U.S. Census Bureau’s Decennial Census is conducted once every ten years. During the Decennial Census, the Census Bureau strives to count every single person and every single residence using what was, prior to 2010, known as the “Short Form.” Decennial Census data are released down to the Census Block level. The data provided in the Decennial Census is much more accurate than the data available from the American Community Survey (ACS), which replaces what was known as the Decennial Census “Long Form.” However, since the Decennial Census is only conducted once every 10-years, the data are not as up to date as that provided by the ACS (Except for the year of Decennial Census data release).
The U.S. Census Bureau’s ACS sends out approximately 3.5-million surveys to nationwide households annually, approximately 135 households per Tract, nationwide, over a 5-year period. The ACS has a final approximate response rate of 67%, or 2.3-million surveys. This means that approximately 13,300 or 1.85% of 717,124 Total Households (Per 2021 ACS 5-Year estimates) in Bexar County respond to an ACS survey in a single year.
ACS 5-year estimates include survey results from 5-years, such as from 2017 to 2021 for the 2021 ACS 5-year estimates. The approximate 66,502 or 9.27% of Total Households within Bexar County responding to the ACS survey over a 5-years period, are the basis for numbers released that represent all households in the county. While the ACS data are more up-to date then Decennial Census data, they are less accurate due to the small sample size and Margin of Error.
Several 2021 ACS 5-Year Estimates tables were used to create the EquityScore GIS data layer attribute table, and the Equity Atlas companion data tables, EquityScoreAdditionalVariables and EquityScoreSpecialVariables. Those ACS tables are:
1. DP02 SELECTED SOCIAL CHARACTERISTICS IN THE UNITED STATES
2. DP04 SELECTED HOUSING CHARACTERISTICS
3. DP05 ACS DEMOGRAPHIC AND HOUSING ESTIMATES
4. S1701 POVERTY STATUS IN THE PAST 12 MONTHS
5. S1903 MEDIAN INCOME IN THE PAST 12 MONTHS (IN 2017 INFLATION-ADJUSTED DOLLARS)
Split Tracts and Data Allocation:
A couple of issue arise with using the more up to data annually released ACS Census Tract estimates. These issues involve splitting Tracts and allocating demographic values between the split portions of Tracts.
First, Census Tract boundaries do not align with the CoSA boundary, and some Tracts are thus split by the CoSA boundary. To address this, when the portion of a Tract intersecting the CoSA was reduced to a very small area (e.g., Less than 10 Acres) or the intersecting portion is very long and exceedingly narrow sliver, those areas were merged with adjacent Tracts within the CoSA to avoid map clutter. The demographic data of the merged small area/sliver (Typically small counts, if any) do not convey to the Tract with which it was merged since it is important that the demographic values allocated to the portions of split Tracts add up to the original Tract’s values for quality assurance procedures. Instead, that value was added to the majority area portion of the original Tract that is outside the CoSA.
Second, the count values (e.g., Total Population, Race/Ethnicity, High School Education…) of a split by the CoSA boundary Tract need to be divided between the sub-portions of the Tract in a way that acknowledges the fact that population is often not evenly distributed within Tract areas. To address this, two allocation methods were used. The Dasymetric Allocation method divided the 2021 ACS 5-year Tract estimates values within its source Track, based on the 2020 Decennial Census total population values of sub-Tracts area Blocks. For instance, if Tract 1 had 10% of its 2020 Decennial Census Total Population within its Block A, then Block A would be assigned 10% of that Tract’s 2021 ACS Total Population. This methodology approximates population densities within a Tract. For variables with averages rather than counts (e.g., Median Household Incomes), portions of split Tracts retain the original values.
Blocks can also be split by the CoSA boundary. To address this, the Areal Allocation method divided split sub-Tract Block areas based on the percentage of the total area within or without the CoSA boundary. For instance, if a Block had a Dasymetric Allocation assigned Total Population value of 200, and that Block was split so that 75% of its area was in the CoSA, then that portion of the Block intersecting the CoSA was assigned a Total Population value of 150.
Equity Score Assignment:
Following the Split Tract Data Allocation, the CoSA Total Population was calculated as being 1,440,704. This value must be used rather than the Census Bureau’s ACS 5-Year estimate Total Population for the CoSA, 1,434,540, since the allocated values for all the Tracts must add up to the Total Population value. Discrepancies between the allocated from Tracts with the CoSA Boundary value and the Census Bureau CoSA value are minor (+6,164) and at least partly attributable to CoSA boundary changes in recent years (Census Bureau does not update their boundaries as frequently). For the People of Color, Median Household Income, Education and Language Equity Scores, the goal is to have approximately 20-percent of the Tract allocated CoSA Total Population, 288,141, in each of the 5 Equity scores (1-5) for a particular variable.
People of Color Score:
Since Hispanics (An ethnicity) are usually treated as a race, it is important to note that the Hispanic or Latino by Race table is used. This table includes a Hispanic and Latino value, as well as Not Hispanic and Latino race values (e.g., Not Hispanic or Latino White, Black or African American, Asian…). The use of this table, rather than the Hispanic and Latino value and the regular Race table, is necessary in order to sum the Race/Ethnicity populations and come up with the correct Total Population value.
The values for the People of Color variable are the sum of all Race/Ethnicity categories, except for the White Alone, Not Hispanic or Latino variable. The Percent People of Color (People of Color / Total Population) variable is symbolized in five classes with each class representing as near as possible, 20% of the above referenced total population. This was accomplished by sorting the Percent People of Color values from high to low and then, starting from the top, selecting records until the target summed Total Population, 288,141, was as close as possible for those selected records. Scores of five were given to the highest values of Percent People of Color. Scores decreased, in turn, to one for the lowest values of Percent People of Color.
Income Score:
The Median Household Income variable was sorted from low to high. Then, starting from the top, records were selected until the target summed Total Population, 288,141, was as close as possible for those selected records. Scores of five were given to the lowest values of Median Household Income. Scores decreased, in turn, to one for the highest values of Median Household Income.
Overall Score:
The Overall Equity score was calculated by adding the People of Color and Median Household Income scores. This results in nine Overall Equity scores (2-10).
Education Score:
The Percent Less than High School Graduate or Equivalent (Less than High School Graduate or Equivalent / Educational Attainment Age 25-Years and Up Total Population) variable values were sorted from high to low. Then, starting from the top, records were selected until the target summed Total Population, 288,141, was as close as possible for those selected records. Scores of five were given to the highest values of Percent Less than High School Graduate or Equivalent. Scores decreased, in turn, to one for the lowest values of Percent Less than High School Graduate or Equivalent.
Language Score:
The Percent Speaks English Less than "Very Well” (Speaks English Less than "Very Well" / Language Spoken at Home Age 5-years and Up Total Population) variable values were sorted from high to low. Then, starting from the top, records were selected until the target summed Total Population, 288,141, was as close as possible for those selected records. Scores of five were given to the highest values of Percent Speaks English Less than "Very Well." Scores decreased, in turn, to one for the lowest values of Percent Speaks English Less than "Very Well."
Data Used in Equity Score Determination:
The EquityScore GIS data layer attribute table only contains the actual Equity Scores or Ranks. The variables used to determine those scores (TOTAL_POP, PCT_PEOPLE_OF_COLOR, MED_HSHLD_INCOME_TOTAL_HSHLDS, PCT_EDU_LESS_THAN_HS_GRAD, and PCT_SPEAK_NOT_ENGLISH) are in the EquityScoreAdditionalVariables companion table. That companion table can be joined to the EquityScore GIS data layer attribute table via the COSA_TRACTID_COMBO variables located in both tables.