A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 
References

A

Abortion—the termination of pregnancy from whatever cause before the fetus is capable of extrauterine life. See induced termination of pregnancy and fetal deaths.

Active theme—when a theme is active it appears slightly raised in the map sidebar. To make a theme active, click on it. To make more than one theme active, hold down SHIFT when you click on the themes. Many of the operations you can perform on a view work on the active theme(s), so making a theme active is the first step for many procedures. For example, when you use the mouse to select features on a view, features are only selected from the active theme(s).

Address geocode—also referred to as address matching. See geocode.

Adolescent age—people aged 13–17 years.

American Indian or Alaska Native (race)—a person having origins in any of the original peoples of North and South America (including Central America), and who maintains tribal affiliation or community attachment.

Area—1. a level of spatial measurement referring to a two-dimensional defined space. A polygon on the earth as projected onto a horizontal plane is an example of an area. Examples: states, counties, lakes and census tracts. 2. polygon. See geographic feature.

Asian (race)—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.

Attribute—1. a characteristic of a geographic feature described by numbers, characters, images and drawings, typically stored in tabular format and linked to the feature by a user-assigned identifier (e.g., the attributes of a hospital might include number of beds and perinatal level of care). 2. a column in a database table.

Attribute table—tabular file linked to a geographic file that contains information about the geographic features on a map. See table.

B

Birth rate—number of births per 1,000 women. See fertility rate.

Birthweight—an infant's weight at or shortly after birth.

Black (race)—a person having origins in any of the black racial groups of Africa.

Buffer—a zone of a specified distance around geographic features. Buffers are useful for proximity analysis (e.g., find all teen births within 10 miles of a teen clinic).

C

Cartesian coordinate system—a two-dimensional, planar coordinate system in which x measures horizontal distance and y measures vertical distance. Relative measures of distance, area and direction are constant throughout the Cartesian coordinate plane.

Centroid—a point, interior to a polygon, whose coordinates are the averages of the corresponding coordinates for all the points joined to produce the polygon. It is the visual center of the polygon, and is sometimes used as the location to which the polygon's attributes are tagged.

Childbearing age—women aged 15–44 years. (See also reproductive age).

Class—a description of a group of objects with similar properties, common behavior, common relationships, and common semantics.

Class hierarchy—a tree structure that represents the inheritance relationship among a set of classes.

Classification, thematic scheme—the meaningful organization of values on a thematic map.

Color ramp—the meaningful organization of colors on a thematic map such as from dark to light on a monochromic display. Used to visually communicate the theme's class hierarchy.

Confidence interval—a statement of accuracy based on a statistic whose distribution function is known, for example, the normal distribution function or the bivariate normal distribution function. Probable errors are stated as the difference between 100% and some percentage of confidence. For example, if probable error is 5%, then the result is stated as being "at the 95% confidence level."

Contiguous area (contiguity)—the topological identification of adjacent polygons.

Coordinate—a set of numbers that designate location in a given reference system, such as x,y in a planar coordinate system or an x,y,z in a three-dimensional coordinate system. Coordinates represent locations on the earth's surface relative to other locations.

Coordinate pair—a set of cartesian coordinates (east-west and north-south distance, or latitude and longitude) describing the two-dimensional location of a point, center of a line or centroid of a polygon, from some known reference datum.

Coordinate system—a reference system used to measure horizontal and vertical distances on a planimetric map. A coordinate system is usually defined by a map projection, a spheroid of reference, a datum, one or more standard parallels, a central meridian, and possible shifts in the x- and y- directions to locate x,y positions of point, line, and area features.  A common coordinate system is used to spatially register geographic data for the same area.

Coverage—1. a digital version of a map forming the basic unit of vector data storage.  Associated feature attribute tables describe and store attributes of the geographic features of the coverage. 2. a set of thematically associated data considered as a unit. A coverage usually represents a single theme. See theme, layer.

D

Data smoothing—a mathematical technique for removing short- range, erratic variation from lines, surfaces or data series.

Database— a logical collection of interrelated information, managed and stored as a unit. A GIS database includes data about the spatial location and shape of geographic features recorded as points, lines, areas, pixels, grid cells, or tins, as well as their attributes.

Datum—a set of parameters and control points used to accurately define the three-dimensional shape of the Earth (e.g., as a spheroid). The datum is the basis for a planar coordinate system. For example, the North American Datum for 1983 (NAD83) is the datum for map projections and coordinates within the United States and throughout North America.

Digital elevation model—1. a digital representation of a continuous variable over a two-dimensional surface by a regular array of z values referenced to a common datum. Digital elevation models are typically used to represent terrain relief. Also referred to as 'digital terrain model' (DTM). 2. an elevation database for elevation data by map sheet from the National Mapping Division of the U.S. Geological Survey (USGS). 3. the format of the USGS digital elevation data sets.

Demographic group—a subpopulation of persons defined by the characteristics they share. Common demographic groups include age, race, ethnicity and gender which are defined at birth, but other groups are defined by medical, behavioral and environmental risk factors such as diabetics, smokers, or persons who live in high crime areas.

Demography—the statistical study of human populations especially with reference to size and density, distribution, and vital statistics.

E

Early neonatal—the early neonatal period commences at birth and ends at seven completed days after birth.

Ecology—1. (human) the spatial and temporal interrelationships between humans and their economic, social, and political organization. 2. the interrelationship of organisms and their environments.

Environment —1. the complex of physical, chemical, and biotic factors (as climate, soil, and living things) that act upon an organism or an ecological community and ultimately determine its form and survival. 2. the aggregate of social and cultural conditions that influence the life of an individual or community.

Ethnicity—the concept of an ethnic group forms the connection between culture and society. The term designates the social group which sets itself apart from other groups on account of specific cultural traits, not only in a few details-food, clothing-but also in a complex of fundamental options-cosmogony, system of values, political organization. Every person shares culture at different levels from local to regional, national and beyond.

F

Feature—see geographic feature.

Feature table—tabular file that stores information about a set of features. Each record corresponds to one feature. A feature table always has a field named "Shape" whose value is an object that is the shape of the corresponding feature. The table also contains attributes for the features. See table.

Fertility rate—number of births per 1,000 women. See birth rate.

Fetal death (dead born)—(WHO) death prior to the complete explusion or extraction from its mother of a product of conception, irrespective of the duration of pregnancy. The death is indicated by the fact that after separation, the fetus does not breathe or show any other evidence of life. (RH Atlas) dead born child of at least 22 weeks gestation.

Fetal loss—see fetal death.

Field—in a database or attribute table, another term for column. See attribute.

FIPS codes—geographic codes used by federal agencies. For more information on FIPS codes go to http://www.itl.nist.gov/fipspubs/.

G

GATHER—(Geographic Analysis Tool for Health and Environmental Research) is a spatial data access tool that provides members of the public health community and general public access to spatial data that is pertinent to the analysis and exploration of public health issues.

Geocode—the process of identifying the coordinates of a location given its address. For example, an address can be matched against a TIGER street network to determine the location of a home. Also referred to as address geocoding or address matching.

Geographic feature—a user-defined geographic phenomenon that can be modeled or represented using geographic data sets in a map application. Examples of geographic features include schools, hospitals, accident sites, streets, service areas, and counties.

Georeference—to establish the relationship between page coordinates on a planar map and known real-world coordinates.

Gestation—the period between conception and birth usually about 280 days.

Global positioning system—a system of satellites and receiving devices used to compute positions on the Earth. GPS is used in navigation, and can be surprisingly precise, (i.e., within 6 inches).

Gravity model—a methodology used in the geography, engineering and social sciences to model the behavior of populations. The underlying assumption of the gravity model is that the influence of populations on one another is inversely proportional to the distance between them. This approach is analogous to the view of gravitational attraction from Newtonian physics.

Grid—a geographic data model representing information as an array of equally sized square cells arranged in rows and columns. Each grid cell is referenced by its geographic x,y location. 

H

Hillshade—technique for making hypsography on a map appear three dimensional by the use of graded shadow effects. Generally, the features are shaded as though illuminated from the northwest.

Hispanic (ethnicity)—a person of Cuban, Mexican, Puerto Rican, South or Central American, or other Spanish culture or origin, regardless of race. Also know as Latino.

Hypsography—topography referred to the national geodetic vertical datum of 1929. The science or art of describing heights of land surfaces with reference to this datum.

I

Imagery—a graphic representation or description of a scene, typically produced by an optical or electronic device. Common examples include remotely sensed data (e.g., satellite data), scanned data, and photographs. An image is stored as a raster data set of binary or integer values that represent the intensity of reflected light, heat, or other range of values on the electromagnetic spectrum.

Incidence rate—the rate at which people without a health problem develop the problem during a specific time, (i.e., the number of new cases developing in a population over a period of time).

Induced termination of pregnancy (ITOP)—to cause the termination of a pregnancy usually before the fetus is capable of extrauterine life.

Infant—a child between the ages of birth and 365 days.

K

Kriging—an optimized interpolation technique (named after Dr. D. G. Krige) that uses information about the stochastic (random, local) aspects of spatial variation.

L

Landsat—a series of satellites that produce images of the earth. The Landsat remote sensing satellite program was developed by NASA (National Aeronautics and Space Administration). Landsat data are provided in .BIL (band interleaved by line) or .BIP (band interleaved by pixel) formats.

Latitude—measures angles in a north-south direction. Defines the y—coordinate of a cartesian coordinate pair.

Latitude/Longitude—a spherical reference system used to measure locations on the Earth's surface. Latitude and longitude are angles measured from the Earth's center to locations on the Earth's surface.

Longitude—measures angles in the east-west direction. Defines the x—coordinate of a cartesian coordinate pair.

Late fetal death—a deadborn child of at least 28 weeks’ gestation.

Latino—ethnic origin. A person of Cuban, Mexican, Puerto Rican, South or Central American, or other Spanish culture or origin, regardless of race. Also know as Hispanic.

Layer—a thematic set of spatial data described and stored in an geographic database. Layers organize a database or map library by subject matter (e.g., counties, roads, and hospitals). Conceptually, layers in a database or map library environment are equivalent to coverages. See theme.

Legend—the reference area on a map that lists and explains the colors, symbols, line patterns, shadings, and annotation used on the map. The legend often includes the scale, origin, orientation, and other map information.

Line— 1. a one-dimensional spatial measurement having a length and a direction and connecting at least two points. Roads, railroads, telecommunication lines, streams, etc., are all examples of  lines. See geographic feature. 2. a set of ordered coordinates that represents the shape of geographic features too narrow to be displayed as an area at the given scale (e.g., contours, street centerlines, or streams), or linear features with no area (e.g., state and county boundary lines). See also polyline.

Linked data (rate)—a rate or other statistic where both the numerator and denominator information are contained within each record in a database.

Livebirth—complete expulsion or extraction from its mother of a baby, irrespective of the duration of the pregnancy, which after such separation breathes or shows any other evidence of life such as beating of the heart, pulsation of the umbilical cord or definite movement of voluntary muscles, whether or not the umbilical cord has been cut or the placenta is attached.

Low birthweight—a birthweight of less than 2,500 grams (5 lbs 8 oz).

M

Map—an abstract representation of the physical features of a portion of the earth's surface graphically displayed on a planar (2-dimentional) surface. Maps display signs, symbols, and spatial relationships among the features. They typically emphasize, generalize, and omit certain features from the display to meet design objectives (e.g., railroad features might be included in a transportation map but omitted from a highway map).

Map extent—the rectangular limits (x,y - minimum, and x,y -maximum) of the area of the Earth's surface displayed. Typically, the extent of the geographic database (or a portion of it defined by a zoomed—in view) defines the map extent for display.

Map scale—the reduction needed to display a representation of the earth's surface on a map. A statement of a measure on the map and the equivalent measure on the earth's surface, often expressed as a representative fraction of distance, such as 1:24,000 (one unit of distance on the map represents 24,000 of the same units of distance on the Earth). Map scale can also be expressed as a statement of equivalence using different units; for example, 1 inch = 1 mile or 1 inch = 2,000 feet.

Map unit—the coordinate units in which a feature data source is stored. Map units can be feet, meters, or decimal degrees.

Maternal mortality—a maternal death is the death of a woman while pregnant or within 42 days of termination of the pregnancy, irrespective of the duration and the site of pregnancy, from any cause related to or aggravated by the pregnancy or its management but not from accidental or incidental causes.

Maternal mortality rate—(NCHS) the maternal mortality rate is the number of maternal deaths per 100,000 live births.

Maternal mortality ratio—the number of maternal deaths per 100,000 live births during the same period.

Meridian—a line running vertically from the north pole to the south pole along which all locations have the same longitude. The Prime Meridian (0) runs through Greenwich, England. From the Prime Meridian, measures of longitude are negative to the west and positive to the east up to 180, halfway around the globe.

Modal age for grade—age of most (mode) children at a given grade level (e.g., most first graders are 6 years of age).

N

Neighbor—See contiguous area.

Neonatal—the neonatal period commences at birth and ends at 28 completed days after birth.

P

Perinatal period—(NCHS) the perinatal period commences at 28 completed weeks of gestation and ends seven completed days after birth.

Period data (rate)—a rate or other statistic where the numerator and denominator information are obtained from different databases or different records within a database.

Pixel—a contraction of the words picture element. The smallest unit of information in an image or raster map. Referred to as a cell in an image or grid.

Planimetric map—map that presents only the horizontal positions for features represented. distinguished from a topographic map by the omission of relief in measurable form. The features usually shown on a planimetric map include rivers,  cities, transportation routes, and  political and private boundary lines.

Point—1. a single x,y coordinate that represents a geographic feature too small to be displayed as a line or area; for example, the location of a mountain peak or a building location on a small-scale map. It is not possible to have point and polygon features in the same layer or coverage. When representing point features, the x,y location of the label point describes the location of the feature. When identifying polygons, the label point can be located anywhere within the polygon such as the centroid.

Polygon—a coverage feature class used to represent areas. A polygon is defined by the arcs that make up its boundary and a point inside its boundary for identification.

Polyline—any line defined by three or more points. Line features in themes such as boundaries, roads, streams and streets are usually polylines. See line.

Postneonatal—the postneonatal period commences at 8 days and ends 364 completed days after birth.

Preterm—less than 37 completed weeks of gestation.

Prevalence rate—a measure of the total number of people (old and new cases) in a population who have a health problem at a specified point in time (usually used for chronic conditions like diabetes).

Q

Quantiles—any of the n–1 values that divide the items of a frequency distribution into n classes with each containing one nth of the total population.

R

Race category—subpopulations of people loosely based on biological and anthropological concepts, and developed in response to needs for collecting standardized data to be used by federal agencies for record keeping, collection and presentation of data (i.e., federal surveys, the decennial census and monitoring various civil rights laws).

Raster—a cellular data structure composed of rows and columns for storing images. Groups of cells with the same value represent features.

Rectification—the process by which an image or grid is converted from image coordinates to real-world coordinates. Rectification typically involves rotation and scaling of grid cells, and thus requires resampling of values.

Referential integrity—the capability to ensure that changes to one table that affect other tables are transmitted to those other tables.

Region—a coverage feature class used to represent a spatial feature as one or more polygons. Many regions can be defined in a single coverage.

Relative standard error (RSE) of a rate—is the estimated standard deviation of a rate based on its numerator and denominator together. RSE is commonly calculated as part of the equation to determine the confidence interval around a rate, however, it can be used alone as a measure of statistical stability where event numbers are low and can fluctuate greatly.

Remote sensing—acquiring information about an object without contacting it physically. Methods include aerial photography, radar, and satellite imaging.

Route—a feature class that is part of the route-system data model used to represent linear features. Routes are based on an arc coverage and are defined as an ordered set of sections. Because sections represent the portion of an arc used in a route, routes do not have to begin or end at nodes.

Reproductive age—1. traditionally defined as 15 to 44 years 2. in the atlas, the definition has been expanded to 10 to 54 years except where specifically noted otherwise. See also childbearing age.

S

Side bar, map—the margin to the immediate left of the map that contains the map layers, and associated layer legends.

Side bar, page—the margin on the left side of the page that contains navigation options on the help pages; and global or demographic choices on the interactive map and table pages.

Soundex—1. a phonetic spelling (up to six characters) of a street name, used for address matching. Each of the 26 letters in the English alphabet are replaced with a letter in the soundex equivalent: Where possible, geocoding uses a soundex equivalent of street names for faster processing. During geocoding, initial candidate street names are found using soundex, then real names are compared and verified. 2. the procedure of encoding a string based on the soundex method developed by Margaret K. Odell and Robert C. Russell.

Shapefile—spatial data format developed and used by ESRI for their ArcView software application.

Standard census geographic hierarchy—an hierarchical geographic presentation that shows the geographic entities in a superior/subordinate structure. The structure is derived from the legal, administrative, and areal relationships of the entities. The hierarchical structure is depicted in report tables by means of indentation. The structure of the standard census geographic hierarchy is: census block, within block group, within census tract, within place, within county subdivision, within county, within state, within division, within region, within the United States.

State plane coordinate systems—a complete system of coordinate systems by which Cartesian coordinates are assigned to all 50 states. The system consists of as many zones as are necessary to define coordinate systems where the scale distortion introduced by the projection is less than one part in 10,000. To achieve this objective, different states use different projections, and many states require more than one zone. For example, the state of Idaho, whose largest extent is north/south, uses the Transverse Mercator projection, and because of its size, requires three separate zones to achieve distortion less than one part in 10,000 within any zone.

Stratum (strata)—1. a statistical subpopulation 2. one of a series of layers, levels, or gradations in an ordered system.

Surveillance—a dynamic process in which data on the occurrence and distribution of health or disease in a population are collected, collated, analyzed, and disseminated.

T

Table—A set of data elements that has a horizontal dimension (rows) and a vertical dimension (columns) in a relational database system. A table has a specified number of columns but can have any number of rows. A table is often called a relation. Rows stored in a table are structurally equivalent to records from flat files in that they must not contain repeating fields.

Teen age—people aged 10–19 years.

Territories (US)—island nations located in the Pacific and Caribbean Oceans that are considered possessions of the United States and report vital statistics data to NCHS. Specifically they are American Samoa, Guam, and the Northern Mariana Islands in the Pacific; and Puerto Rico and the Virgin Islands in the Caribbean.

Theme—1. a user-defined perspective on a map layer that is specified, if applicable, by a layer name and feature class or data set name, attributes of interest, a data classification scheme, and theme-specific symbology for drawing. See layer.

TIGER database—TIGER® is an acronym for the Topologically Integrated Geographic Encoding and Referencing (System or database). It is a digital (computer-readable) geographic database that automates the mapping and related geographic activities required to support the U.S. Census Bureau’s census and survey programs. The U.S. Census Bureau developed the TIGER System to automate the geographic support processes needed to meet the major geographic needs of the 1990 census: producing the cartographic products to support data collection and map presentations, providing the geographic structure for tabulation and dissemination of the collected statistical data, assigning residential and employer addresses to the correct geographic location and relating those locations to the geographic entities used for data tabulation, and so forth. The content of the TIGER database is undergoing continuous updates and is made available to the public through a variety of TIGER /Line® files that may be obtained free of charge from the Internet or packaged on CD-ROM or DVD from Customer Services, U.S. Census Bureau, Washington, D.C. 20233–1900; telephone 301-457-4100; Web site http://www.census.gov/geo/www/tiger.

Triangulated irregular network (TIN)—A data structure used to define a three—dimensional surface as a series of irregular triangles. Used for efficient analysis in terrain modelling because any geographic shape can be accurately represented by the sides of triangles, given that they are sufficiently small. Where large flat areas are to be defined, larger triangles can be used. The tin data set includes topological relationships between points and their neighboring triangles. Each sample point has an x, y coordinate and a surface, or z-value. These points are connected by edges to form a set of non-overlapping triangles used to represent the surface. Tins are also called irregular triangular mesh or irregular triangular surface model.

Topographic map—a map containing contours indicating lines of equal surface elevation (relief), often referred to as topo maps.

Topology—the spatial relationships between connecting or adjacent coverage features (e.g., arcs, nodes, polygons, and points). For example, the topology of an arc includes its from- and to- nodes, and its left and right polygons. Topological relationships are built from simple elements into complex elements: points (simplest elements), arcs (sets of connected points), areas (sets of connected arcs), and routes (sets of sections, which are arcs or portions of arcs). Redundant data (coordinates) are eliminated because an arc may represent a linear feature, part of the boundary of an area feature, or both. Topology is useful in GIS because many spatial modeling operations don't require coordinates, only topological information. For example, to find an optimal path between two points requires a list of the arcs that connect to each other and the cost to traverse each arc in each direction. Coordinates are only needed for drawing the path after it is calculated.

Transparent layers—polygon layers that are outlined but have no fill or transparent fill that allows the map features in the layer(s) below to be viewed. They are used to highlight specific areas of a map or to group map features.

V

Vector—1. a coordinate-based data structure commonly used to represent linear geographic features. Each linear feature is represented as an ordered list of vertices. Traditional vector data structures include double-digitized polygons and arc-node models. 2. A directed line segment whose magnitude is represented by the coordinates for the pair of end points. See also vector representation.

Vector data—an array of data with one dimension (i.e., a list of values).

Vector representation—a method of internal coding of graphic data in which the map area is viewed as a series of points (whose coordinates are measured). Some points are joined by lines (vectors), and some line segments (arcs) are joined to form polygons. This method allows for very accurate representation through accurate measurement and recording of coordinates. The topology (the relationship of points, lines and areas) allows for very accurate spatial analyses, though algorithms are typically slower than for corresponding raster-based data. Network and routing analyses are very easy and efficient. Data volumes are usually much smaller than for corresponding raster-based data. Most Geographic Information Systems require both vector representation and raster representation for efficient storage and analyses of a variety of graphic data. Algorithms exist for conversion between representations, though raster-to-vector is a good deal more complex and time consuming than vice versa. Compare Raster representation.

View—1. the visible area of a computer generated map including various map elements which may alternatively be expressed or suppressed within a view, creating a unique representation based on the visible information. 2. the method for grouping and displaying the analysis layer defined by political boundaries such as a state, region or division. For example: Texas would be an example of a state view, and New England would be an example of a census division view.

Visibility—in a map view, layers are visible if 2 conditions are met: 1. visibility is enabled by checking the visibility box in the map side bar, and 2. the scale of the map view is zoomed in sufficiently close to provide a meaningful display.

W

Waypoint—in a GPS, a waypoint represents the x,y coordinates of the location being geocoded.

White (race)—a person having origins in any of the original peoples of Europe, the Middle East, or North Africa.

X

X coordinate—see longitude.

Y

Y coordinate—see latitude.

Z

ZIP codes—(zone improvement plan) a 5–digit code that identifies a specific geographic delivery area. ZIP Codes can represent an area within a state, an area that crosses state boundaries (unusual condition), or a single building or company that has a very high mail volume.

ZIP+4—describes the last four positions of a ZIP+4 Code. Most delivery addresses are assigned a single ZIP+4 Code. However, large companies may be given a range of ZIP+4 Codes that can be used to route mail to a specific department.

Zoom—a capability for proportionately enlarging or reducing the scale of a computer generated figure or map displayed on a computer monitor.  

References

1. Wilcox, LS & Marks, JS (eds). From Data to Action: CDC's Public Health Surveillance for Women, Infants and Children. Monograph. Centers for Disease Control and Prevention, Public Health Service, U.S. Department of Health and Human Services.

2. Glossary of GIS Terms, Environmental Systems Research Institute (ESRI), Redmond, CA., http://www.gis.com/resources/library/dictionaries.html

3. Glossary of Cartographic Terms, UT Library Online, University of Texas at Austin, Austin, TX., http://www.lib.utexas.edu/Libs/PCL/Map_collection/glossary.html*

4. Glossary from The Geographer's Craft, The Geographer's Craft Project, Department of Geography, University of Colorado at Boulder, Boulder CO., http://www.Colorado.EDU/geography/gcraft/gloss/glossary.html*

5. Census 2000 Geographic Terms and Concepts, U.S. Census Bureau, Census 2000.

6. Collegiate® Dictionary, Merriam—Webster Online, http://www.m—w.com/

7. NCHS Definitions, National Center of Health Statistics.

Page last reviewed: 7/28/08
Page last modified: 1/29/07
Content source: Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion