Population Definitions

• Mapping Units
• Visible Layers
• Base Layers
• Definitions
• Map Tools

Presentation Information

• All numbers and rates pertain to the place of residence (not occurrence).
• If an Age group, Race, Sex, Ethnicity or Education Level are chosen, all rates/percentages include only the choices in both the numerator and denominator.
• Maps are used to emphasize the spatial distribution of one or more geographic attributes or variables. This site generates choropleth maps as thematic maps in which the geographies are shaded different colors to represent different magnitudes of a variable.
• The map projection is Lambert Conformal Conic.

Confidentiality rule:

Numbers based on 0-4 events are classified as a separate static class when a sub-county level geography (Census Tract or County Commission District) is chosen. This is done to assure confidentiality.

Not Reportable

At the County level or higher rates (and percents) based on 1-4 events are not reported due to statistical reliability reasons. At sub-county level (Census Tract or County Commission District), rates and percents based on 0-4 are not reported. This assures confidentiality.

Trendable Maps

Trendable maps are a series of choropleth maps showing change in spatial distribution of data in a selected area over selected period of time. Trendable maps share the same data class breaks which allows easy comparison between each map in the series.

Mapping Units:

• County to create a map of a selected geography: counties, Public Health District(s) or Perinatal Region(s); or
• Public Health District to create a map of the state by the 18 Public Health Districts; or
• Perinatal Region to create a map of the state by the 6 Perinatal Regions.

Visible Layers:

Cities/Towns

A mix of both incorporated places (legal entities) and census designated places or CDPs (statistical entities). An incorporated place is established to provide governmental functions for a concentration of people. Places always nest within a state, but may extend across county and county subdivision boundaries. An incorporated place usually is a city, town, village, or borough, but can have other legal descriptions. CDPs are delineated to provide data for settled concentrations of population that are identifiable by name, but are not legally incorporated under the laws of the state in which they are located. Click on city/town name to highlight the boundary. Reference Source: U.S. Census, 2020.

GA House Districts

Electoral districts from which State Representatives are elected. The Georgia Constitution requires not less than 180 Representatives apportioned by population from representative districts. Layer Source: https://www.legis.ga.gov/, Adopted 2023 – Effective for 2024 Elections.

GA Senate Districts

Electoral districts from which State Senators are elected. The Georgia Constitution limits the number to not more than 56 single member districts. Senate districts are apportioned based on population. Layer Source: https://www.legis.ga.gov/, Adopted 2023 – Effective for 2024 Elections.

Hospitals

Hospitals are the non-Federal acute-care inpatient medical facilities in Georgia. Click on the symbol to get the name. Reference Source: Georgia Hospital Association, 2021.

Interstates

Interstates are the freeways that are part of the Interstate Highway System in Georgia. The Interstate Highway System connects major cities within the United States. Click on the line to get the Interstate number. Layer Source: Esri, March 1, 2012.

Major Roads

Major roads are a combination of both federal and state highways connecting cities and towns. Click on the line to get the route number. Layer Source: Esri, March 1, 2012.

Perinatal Regions

The Perinatal Regions were established by the Department of Public Health in cooperation with the six teaching hospitals located in Atlanta, Albany, Augusta, Columbus, Macon and Savannah. The Regions reflect the hospital referral patterns for high risk pregnant women and newborns Each of the six hospitals has a Regional Perinatal Center which has contracts with the state and receives funding to care for high risk pregnant women and infants as well as to train staff from other hospitals in perinatal care especially for high risk patients. Reference Source: Georgia Department of Public Health, March 2005.

ZIP Code

Established by the U.S. Postal Service for distribution of mail. Zip codes do not generally respect political boundaries or census areas such as tracts. Zip codes usually do not have clearly identifiable boundaries, often serve a continually changing area, are changed periodically to meet postal requirements, and do not cover all land area in the U.S. Layer Source: Esri, June 1, 2020.

Base Layers:

Base layers are background information to provide contextual references for local-level maps. They are especially suited for tract-level maps and give real-world reference to maps you create in OASIS. There are three toggle-able (on/off) base layers:

Demographic Clusters

Demographic Clusters refer to the socioeconomic status classifications created by OHIP, and are at the census block-group level. More information here: https://oasis.state.ga.us/gis/demographiccluster/DemoClusters2011.htm

Aerial Photography

Aerial Photography refers to ESRI's World Imagery.

Socioeconomic Vulnerability

Socioeconomic Vulnerability refers to the socioeconomic status domain/subset of the CDC’s Social Vulnerability Index (SVI), and is at the census tract level. Socioeconomic vulnerability ranks tracts within the state on 5 factors: below 150% poverty, unemployed, housing cost burden, no high school diploma, and no health insurance. Percentile ranking values range from 0 to 1, with higher values indicating greater vulnerability/lower socioeconomic status. Quintiles were used to create class breaks. For more information see https://www.atsdr.cdc.gov/placeandhealth/svi/index.html. For data dictionary click here.

Street Map

Street Map refers to ESRI's World Street Map with street-level data for North America.

Data Classification Methods:

Natural Breaks (Jenks)

This method minimizes within-class variance and maximizes between-class variance in an iterative series of calculations. This method seeks to partition data into classes based on natural groups in the data distribution. Natural breaks occur in the histogram at the low points of valleys. Breaks are assigned in the order of the size of the valleys, with the largest valley being assigned the first natural break.

George F. Jenks is considered a pioneer in GIS educational programs. Through an award from the Fund for Advancement of Science, Jenks identified four key objectives for cartographic training. Robert McMaster and Susanna McMaster; A History of Twentieth-Century American Academic Cartography

Source: Brewer and Pickle. Evaluation of Methods for Classifying Epidemiological Data on Choropleth Maps in a Series. Annals of the Association of American Geographers, 92(4), 2002, pp. 662-681.

Quantiles

• Data values for each enumeration unit (e.g. county or census tract) are ranked from lowest to highest.
• The total number of values is divided by the number of classes specified by the user to determine how many values each class will contain. The object is to obtain a roughly equal number of data values within each class. For example, if you have 100 census tracts and the tract data values are to be classed into 5 classes, each class will have 20 values (100/5 = 20).
• In some cases, an equal number of values will not be placed into each class. For instance, if there are an odd number of enumeration units some classes will have a larger number of data values than others. If data values for the 159 counties of Georgia are divided into 4 classes, then some classes might have 39 data values while others have 40. In addition, identical data values are maintained within the same classes. Continuing the Georgia county example, if 45 of the lowest data values are 0, then the lowest class will have 45 data values all with a value of 0.

The quantiles method of classification is provided because:

• Quantiles classification is one of the simplest methods of classification and is easy to understand and interpret.
• Classes are usually centered on the median, a measure of central tendency, and "they group enumeration units above and below the median into classes with equal frequencies regardless of their values." This makes maps easier to compare with one another.
• Many health-related measures are distributed normally (i.e. a large number of values falling near the middle of the data range with a smaller number of values on the low and high ends of the data range) making quantiles classification a logical classification method.

Source: Brewer and Pickle. Evaluation of Methods for Classifying Epidemiological Data on Choropleth Maps in a Series. Annals of the Association of American Geographers, 92(4), 2002, pp. 662-681.

Definitions:

Age

Ages are presented by Detailed Age Groups, Lifestages and Single Year of Age which is created by the Department of Public Health, OHIP. Also, note that selecting "all ages" will supercede any start and end age selection. Uncheck "all ages" to make an age-specific selection.

Ethnicity

Hispanic or Latino includes persons of Mexican, Puerto Rican, Cuban, South or Central American, or other Spanish culture or origin, regardless of race.

Percent of Population within State

The percent of population a cluster, county or district contributes to Georgia population.
Formula = [The number of population in a cluster, county, or district / The number of population in Georgia] *100.

Population Estimates

Population data for years 1994-1999 are the National Center for Health Statistics Bridged-race estimates. These estimates were replaced by the Census' post-censal estimates on January 12, 2004. However, single-year estimates were prepared is from the actual Census count, prepared by the U.S. Bureau of the Census. Documentation and file layouts are available from the U.S. Bureau of the Census web site.

Census populations include military, students, and institutionalized persons if in their usual and customary residence. For years 2001 and higher, population estimates data in 5-year groups are also prepared by the U.S. Bureau of the Census. However, single-year estimates were prepared from Census data by the Division of Public Health. NOTE: Cross-tabulated population data were not available from the U.S. Census for year 2001 until September 2003: Before September 2003 the Division of Public Health used 2000 data in year 2001 as well. However, these 2001 population data were updated November 13, 2003 with the 2001 Census data described above.

Race

Per the Federal Office of Management and Budget, Directive 15 (1997),

• White is a person having origins in any of the original peoples of Europe, the Middle East or North Africa;
• Black or African-American is a person having origins in any of the black racial groups of Africa;
• Asian is a person having origins in any of the original peoples of the Far East, Southeast Asia, or the Indian subcontinent including for example, Cambodia, China, India, Japan, Korea, Malaysia, Pakistan, the Philippine Islands, Thailand and Vietnam;
• American Indian/Alaska Native is a person having origins in any of the original peoples of North and South America (including Central American), and who maintains tribal affiliation or community attachment;
• Native Hawaiian or Other Pacific Islander is a person having origins in any of the original peoples of Hawaii, Guam, Samoa, or other Pacific Islands;
• Multiracial is a person declaring 2 or more of these races.

Note: Prior to year 2000 population estimates adhered to a different Federal standard for race: White, Black, Asian or Other Pacific Islander, American Indian and Alaska Native. So, unlike years 2000 and after, Multiracial is not included. Asian by itself is not available because it was grouped with Pacific Islander. After 1999 Asian is separate from Native Hawaiian or Other Pacific Islander. Therefore the mapping tool does not present population maps prior to the year 2000.

Map Tools

	Zoom In: Select this button and then click on the map to enlarge the map. You can also click down and drag your mouse to define an area to zoom to.
	Zoom Out: Select this button and the click on the map to reduce the map. The area where you click will be the center of the map. Note: Select the mouse scroll wheel to zoom in or out.
	Full Extent: Select this button to see the entire map.
	Pan: Select this button to move the map around in any given extent.
	Previous Extent: Click on this button to go back to the previous extent.
	Next Extent: Click on this button to go to the next extent (before previous extent)
	Print Map: Click on this button to get a printable copy of the map in PNG format as it appears at the moment. Disable any pop-up blockers. Right click on the preview and you can choose to save, copy or print the preview. The preview can also be dragged and dropped to a folder or desktop.

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V1.10 (8/13/2024)