Glossary             [A-D] - [E-J] - [K-P] - [Q-S] - [T-Z]

Query*
A question, especially if asked of a database by the user via a database management system or GIS.

Race
Race is a self-identification data item in which respondents choose the race or races with which they most closely identify.
For Census 2000:
In 1997, after a lengthy analysis and public comment period, the Federal Office of Management and Budget (OMB) revised the standards for how the Federal government would collect and present data on race and ethnicity. The new guidelines reflect "the increasing diversity of our Nation's population, stemming from growth in interracial marriages and immigration."
These new guidelines revised some of the racial categories used in 1990 and preceding censuses and allowed respondents to report as many race categories as were necessary to identify themselves on the Census 2000 questionnaire. Note that the full report is available at http://www.whitehouse.gov/omb/inforeg/race.pdf.

How the new guidelines affect Census 2000 results and the comparison with data from 1990:
Census 2000 race data are not directly comparable with data from 1990 and previous censuses. See the Census 2000 Brief, "Overview of Race and Hispanic Origin".
Race Alone categories:
Includes the minimum 5 race categories required by OMB, plus the 'some other race alone' included by the Census Bureau for Census 2000, with the approval of OMB.
      White alone
      Black or African-American alone
      American Indian or Alaska Native alone
      Asian alone
      Native Hawaiian or other Pacific Islander alone
      Some other race alone
Related terms: Asian, Native Hawaiian and Pacific Islander race and ethnic categories, Spanish/Hispanic/Latino

RAM*
The part of a computer's memory designed for rapid access and computation.

Range*
The highest value of an attribute less the lowest, in the units of the attribute.

Raster*
A data structure for maps based on grid cells.

Rate
This is a measure of occurrences in a given period of time divided by the possible number of occurrences during that period.

Ratio
This is a measure of the relative size of one number to a second number expressed as the quotient of the first number divided by the second.

Reapportionment
The redistribution of seats in the U.S. House of Representatives among the several states on the basis of the most recent decennial census as required by Article 1, section 2 of the Constitution. Reapportionment does not affect Puerto Rico.
Related term: Apportionment

Record*
A set of values for all attributes in a database. Equivalent to a row in a data table.

Redistricting
The process of revising the geographic boundaries of areas from which people elect representatives to the U.S. Congress, a state legislature, a county or city council, a school board, and the like, to meet the legal requirement that such areas be as equal in population as possible following a census.
Related terms: Apportionment, Voting District (VTD)

Redraw Map
Displays the newly selected layer on the map.

Reference map*
A highly generalized map type designed to show general spatial properties of features. Examples are world maps, road maps, atlas maps, and sketch maps. Sometimes used in navigation, often with a limited set of symbols and few data. A cartographic base reference map is often the base layer or framework in a GIS.

Related children
Includes all people in a household under the age of 18, regardless of marital status, who are related to the householder. Does not include householder's spouse or foster children, regardless of age.
Related terms: Child, Own children
Related term: Contract rent

Relational DBMS*
A database management system based on the relational data model.

Remote sensing 1
A process of detecting or monitoring an area usually from the air or from space by measuring reflected or emitted radiation. Some satellites carry special instruments while orbiting the Earth to detect the amount of heat being emitted by the planet.

Remotely sensed data*
Data collected by a sensor that is not in direct contact with the area being mapped. Active remote sensing involves transmitting a beam that is detected after reflection; passive remote sensing simply measures light from the sun being reflected by objects being sensed. Similar instruments for remote sensing can operate from aircraft or satellites.

Rental vacancy rate
The proportion of the rental inventory which is vacant for rent. It is computed by dividing the number of vacant units for rent by the sum of the renter-occupied units and the number of vacant units for rent, and then multiplying by 100.
Related term: Homeowner vacancy rate, Renter-occupied housing unit

Renter-occupied housing unit
All occupied units which are not owner occupied, whether they are rented for cash rent or occupied without payment of cash rent, are classified as renter-occupied.
Related term: Owner-occupied housing unit

Representative fraction*
The ratio of a distance as represented on a map to the equivalent distance measured on the ground. Typical representative fractions are 1:1 million, 1:100,000, and 1:50,000.

Reptiles Species Richness - see "Species Richness"

Reservoir 2
A pond, lake, or basin, either natural or artificial, for the storage, regulation, and control of water.

Reset
Unchecks the layers just selected before the Redraw Map button is clicked.

Resident population
Resident population of the United States includes persons resident in the 50 States and the District of Columbia. It excludes residents of the Commonwealth of Puerto Rico, and residents of the island areas under United States sovereignty or jurisdiction (principally American Samoa, Guam, Virgin Islands of the United States, and the Commonwealth of the Northern Mariana Islands). A resident of a specific area for Census 2000 is defined as a person "usually resident" in that area. Resident population excludes the United States Armed Forces overseas, as well as civilian United States citizens whose usual place of residence is outside the United States.
Related terms: Apportionment population, Population

Retrieval*
The ability of a database management system or GIS to get back from computer memory records that were stored there previously.

Riparian 3
Relating to or living or located on the bank of a natural watercourse (as a river) or sometimes of a lake or a tidewater.

Riparian Habitat 4
Areas adjacent to rivers and streams with a differing density, diversity, and productivity of plant and animal species relative to nearby uplands.

Rural
Territory, population and housing units not classified as urban. "Rural" classification cuts across other hierarchies and can be in metropolitan or non-metropolitan areas.
Related terms: Metropolitan, Urban

Sample data*
Population and housing information collected from the census long form for a one in six sample of households in the United States and Puerto Rico, and on a continuous basis for selected areas in the American Community Survey.
Related terms: Census (decennial), Long form

Sampling error
Errors that occur because only part of the population is directly contacted. With any sample, differences are likely to exist between the characteristics of the sampled population and the larger group from which the sample was chosen. Sampling error, unlike nonsampling error, is measurable.

Scale*
The geographic property of being reduced by the representative fraction. Scale is usually depicted on a map or can be calculated from features of known size.

School District
Geographic entities within which state, county, or local officials provide public educational services for the area's residents. The boundaries and names are provided by state officials.

School enrollment
Enrollment in regular school, either public or private, which includes nursery school, kindergarten, elementary school, and schooling which leads to a high school diploma or college degree.
Related terms: Educational attainment, Grade in which enrolled

Search*
Any database query that results in successful retrieval of records.
See also 100 percent data
See also 100 percent data and short form

Server*
A computer connected to a network whose primary function is to act as a library of information that other users can share.

Sex
An individual's gender classification - male or female.

Sex ratio
A measure derived by dividing the total number of males by the total number of females, and then multiplying by 100.

Shapefile
A shapefile is a digital vector (non-topological) storage format for storing geometric location and associated attribute information. The Shapefile format is created by ArcView and can be used by ArcView, ARC/INFO, ArcGIS and other widely used GIS software. (from USGS CMG InfoBank Definitions at: http://walrus.wr.usgs.gov/infobank/programs/html/main/definitions.html)

Short form
The decennial census questionnaire, sent to approximately five of six households for the 1980, 1990, and 2000 censuses. For Census 2000, the questionnaire asked population questions related to household relationship, sex, race, age and Hispanic or Latino origin and housing questions related to tenure, occupancy, and vacancy status. The 1990 short form contained a question on marital status. The questions contained on the short form also are asked on the long form, along with additional questions.
Related terms: Census (decennial), Long form

Show Data
Displays information about any "visible layer" within the map view in a pop-up window when you click on a feature on the map.

Slope*
The constant of multiplication in a linear relationship; that is, the rate of increase of a straight line up or down. See also gradient.

Spanish/Hispanic/Latino
For Census 2000 and the American Community Survey: People who identify with the terms "Hispanic" or "Latino" are those who classify themselves in one of the specific Hispanic or Latino categories listed on the Census 2000 or ACS questionnaire-"Mexican," "Puerto Rican," or "Cuban"-as well as those who indicate that they are "other Spanish, Hispanic, or Latino." Origin can be viewed as the heritage, nationality group, lineage, or country of birth of the person or the person's parents or ancestors before their arrival in the United States. People who identify their origin as Spanish, Hispanic, or Latino may be of any race.
For 1990 Census of Population and Housing:
A self-designated classification for people whose origins are from Spain, the Spanish-speaking countries of Central or South America, the Caribbean, or those identifying themselves generally as Spanish, Spanish-American, etc. Origin can be viewed as ancestry, nationality, or country of birth of the person or person's parents or ancestors prior to their arrival in the United States.

Spanish/Hispanic/Latino people may be of any race.
Listed below are the 28 Hispanic or Latino categories displayed in Census 2000 tabulations:
Mexican
Puerto Rican
Cuban
Dominican Republic
Central American:
      Costa Rican
      Guatemalan
      Honduran
      Nicaraguan
      Panamanian
      Salvadoran
      Other Central American
South American:
      Argentinian
      Bolivian
      Chilean
      Colombian
      Ecuadorian
      Paraguayan
      Peruvian
      Uruguayan
      Venezuelan
      Other South American
Other Hispanic or Latino:
      Spaniard
      Spanish
      Spanish American
      All other Hispanic or Latino
Related terms: Ancestry, Hispanic or Latino origin, Race

Spatial data*
Data that can be linked to locations in geographic space, usually via features on a map.

Spatial data transfer standard (SDTS)*
The formal standard specifying the organization and mechanism for the transfer of GIS data between dissimilar computer systems. Adopted as FIPS 173 in 1992, SDTS specifies terminology, feature types, and accuracy specifications as well as a formal file transfer method for any generic geographic data. Subsets for the standard for specific types of data, vector, and raster, for example, are called profiles.

Spatial distribution*
The locations of features or measurements observed in geographic space.

Species 4
1. A reproductively isolated aggregate of interbreeding organisms having common attributes and usually designated by a common name.
2. An organism belonging to belonging to such a category.

Species Richness 5
The number of species of a particular interest group found in a given area.

Spouse
A person legally married to another person.

Spreadsheet*
A computer program that allows the user to enter numbers and text into a table with rows and columns, and then maintain and manipulate those numbers using the table structure.

Spring 4
Ground water seeping out of the earth where the water table intersects the ground surface.

Standard Industrial Classification (SIC)
Industry classification system that was used in Economic Censuses prior to 1997. This system identifies establishments by the principal activity in which they are engaged. SIC has been replaced by North American Industry Classification System (NAICS) in the 1997 Economic Census.
Related terms: Economic census, North American Industry Classification System (NAICS)

Standard parallel*
A parallel on a map projection that is secant and therefore distortion- free.

State legislative district (SLD)
An area from which members are elected to state legislatures. The SLDs embody the upper (senate) and lower (house) chambers of the state legislature.

State plane*
A coordinate system common in utility and surveying applications in the lower 48 United States and based on zones drawn state by state on transverse Mercator and Lambert conformal conic projections.

Stream 2
A general term for a body of flowing water; natural water course containing water at least part of the year. In hydrology, it is generally applied to the water flowing in a natural channel as distinct from a canal.

Summary file (SF)
Statistics for a large number of geographic areas that are designed to show great subject matter detail presented in tabular form. There are four main summary files produced from the data collected during Census 2000.
See the individual definitions for Summary Files 1, 2, 3, and 4 for a more in-depth explanation of each.
Related term: Census (decennial)

Summary File 1 (SF 1)
This file presents 100-percent population and housing figures for the total population, for 63 race categories, and for many other race and Hispanic or Latino categories. This includes age, sex, households, household relationship, housing units, and tenure (whether the residence is owned or rented). Also included are selected characteristics for a limited number of race and Hispanic or Latino categories. The data are available for the U.S., regions, divisions, states, counties, county subdivisions, places, census tracts, block groups, blocks, metropolitan areas, American Indian areas, tribal subdivisions, congressional districts, and ZIP Code Tabulation Areas.
Related term: Census (decennial)

Summary Tape Files 1-4 (STFs 1-4)
Summary tape files are products of the 1990 Census of Population and Housing. They are summary tabulations of 100-percent and sample population and housing data available for public use on computer tape and CD-ROM.

Summary File 2 (SF 2)
This file presents data similar to the information included in Summary File 1. These data are shown down to the census tract level for 250 race, Hispanic or Latino, and American Indian and Alaska Native tribe categories. For data to be shown in SF 2, a population category must meet a population size threshold of 100 or more people of that specific population category in a specific geographic area.
Related term: Census (decennial)

Summary File 3 (SF 3)
This file presents data on the population and housing long form subjects such as income and education. It includes population totals for ancestry groups. It also includes selected characteristics for a limited number of race and Hispanic or Latino categories. The data are available for the state, counties, places, census tracts, metropolitan areas, American Indian areas, tribal subdivisions, congressional districts, and Zip Code Tabulation Areas.
Related terms: Census (decennial), Long form
See also sample data

Summary File 4 (SF 4)
This file presents data similar to the information included in Summary File 3. These data are shown down to the census tract level for 336 race, Hispanic or Latino, American Indian and Alaska Native tribe, and ancestry categories. For data to be shown in SF 4, there must be at least 50 unweighted sample cases of a specific population category in a specific geographic area. In addition, the data for the specific population category for the specific geographic area must also have been available in Summary File 2.
See also short form.

Superfund 4
The program operated under the legislative authority of the Comprehensive Environmental Response, Compensation, and Liability Act (1980) (CERCLA) and the Superfund Amendments and Reauthorization Act of 1986 (SARA) that funds and carries out EPA solid waste emergency and long-term removal and remedial activities. These activities include establishing the National Priorities List, investigating sites for inclusion on the list, determining their priority, and conducting and/or supervising cleanup and other remedial actions.

Surface water 1
Water on the surface of the Earth exposed to the atmosphere, such as rain, snow, sleet, or hail.

Survey*
A data collection activity involving observation or questionnaires for a sample of a population. (A census is a 100-percent sample survey; it collects information about every member of a population.) Surveys are normally less expensive to conduct than censuses; hence, they may be taken more frequently and can provide an information update between censuses. Often, they are used to collect a wider variety of information than is collected in a census

Symbol*
An abstract graphic representation of a geographic feature for representation on a map. For example, the feature could be a canal, the symbol a blue line of a given thickness.

* Clarke, Keith C. Getting Started with Geographic Information Systems. 4th edition Upper Saddle River, N.J., 2003.
1 USGS Glossary - http://interactive2.usgs.gov/glossary -Page no longer available.
2 USGS Water Science Glossary of Terms - http://ga.water.usgs.gov/edu/dictionary.html
3 Encyclopedia Britannica Online - http://search.eb.com/dictionary
4 EPA Terms of Environment - http://www.epa.gov/OCEPAterms
5 USGS Gap Analysis Program Handbook

All other definitions from American Factfinder - http://factfinder.census.gov/servlet/BasicFactsServlet - click on Glossary

For other Glossaries, see http://www.gis.com/whatisgis/glossaries.html