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The statistics corner: more new products from the Census Bureau.

THE 1990 CENSUS will provide this century's single best "portrait" of our Nation's people and housing. The first block-level data were released in March 1991. By the end of 1993, the 1990 product "line" will grow to include 500,000 published pages and some 85 billion data cells. The data are being used to reapportion the 103rd Congress, distribute some $120 billion in Federal assistance each year, and support countless business decisions.

The volume and diversity of census data can be overwhelming. To help users understand the census data products, this article highlights 1990 changes, discusses major products, and outlines new geographic information.

CHANGES FOR 1990

Data content and products for the 1990 census will be very similar to their 1980 counterparts. Census data collection methods were improved but not fundamentally changed. Data processing operations were reorganized and more automated. However, these processing changes are largely "invisible" to census participants and data users.

Users of previous decennial census data may note three types of changes in 1990 data products: revised content, new products, and earlier release. These changes are modest compared to those in 1980, but may be important for those with specific subject or product interests.

Revised content. Dozens of revisions were made in the 1990 short and long form questions. Many were technical in nature, such as adding categories for higher property values and new racial and ethnic information, and dropping month of birth. Other changes were more substantive. For example, adding categories for household living arrangements, difficulties faced by the disabled, condominium fees, pension income, and for-profit versus not-for-profit employers.

In addition, concern for respondent burden and changing data priorities resulted in some questionnaire deletions. Questions not retained for 1990 included marital history, parochial school attendance, carpooling arrangements, and several housing questions (number of floors, living units and bathrooms; type of heating system; air conditioning; elevator; and water heating and cooking fuels).

New Products. The 1990 census was the first to offer data on compact disc-read only memory (CD-ROM) and on-line formats for use with personal computers. The first CD-ROMs were released in early 1991, providing redistricting counts for states, counties and areas as small as a single block. Future discs will provide additional population and housing statistics, and include data for ZIP Codes.

The Census Bureau's on-line data service is CENDATA, available through commercial vendors. CENDATA carries up-to-the-day product information and summary statistics from many 1990 products. For example, CENDATA carried the press release text and redistricting counts for each state, but the companion state CD-ROM included counts for all geographic levels down to the block level.

Earlier release. The Census Bureau responded to user requests for earlier release of census data through faster production, restructed content, and other product changes. Examples of faster production include issuing the first redistricting file three weeks earlier than in 1980 and with data items not previously included, and releasing the first complete 1990 short-form data on computer tapes nine months earlier than in 1980 and with expanded content.

In addition, structural changes included holding metropolitan and urbanized-area data for later reports, and eliminating Summary Tape File 5 (STF 5) but incorporating key data items into an expanded program of subject reports. Other changes for 1990 include eliminating all preliminary reports, rearranging selected geographic areas in printed reports, and reducing the amount of historical data presented in early reports.

MAJOR DATA PRODUCTS

The 1990 products reflect eight broad data concepts. For each concept, data on computer tapes are the earliest and most detailed product. Some eight weeks after tapes are released, the same or similar data will routinely appear in printed reports, CD-ROM and microfiche.

The sequencing of 1990 data products reflects data source,and geographic area, and subject matter detail. Products based on short-form (100-percent) data precede long-form (17-percent sample) products, general-purpose products come before specialized ones, and U.S. summary data are last in a series. Major 1990 data product concepts are discussed below in approximate order of initial release.

Apportionment and redistricting counts. The reapportionment press release included short-form population counts, and redistricting data include selected population and housing counts for small areas (including voting districts where states identified them). The redistricting file included age-eighteen detail and nationwide block coverage not previously available.

Reapportionment counts by state were released in December 1990. Computer tapes with redistricting data are called the P.L. 94-171 File. These data are also available on compact disc and as hard-copy printouts. Release of the P.L. 94-171 File by state, along with accompanying maps, was completed in March 1991.

Short-form data for small areas. These early products tabulate up to 1,000 cells of information from the fourteen short-form population and housing questions for areas as small as one census block. Geographic data use the full ten-level hierarchy that can aggregate blocks into block groups, block groups into census tracts, and so forth, to reach national summaries. One file (not available on CD-ROM or microfiche) provides data by Congressional District.

Computer tapes of these data are called Summary Tape File 1, and include four separate files (STF 1A, B, C and D). Selected population, housing and geographic details are included in printed reports, CD-ROM discs and microfiche. Printed reports include maps of American Indian and Alaskan Native areas, counties, county subdivisions, and places. The last STF 1A tape files were issued by June 1991, more STF 1 files will be released in 1992, and Congressional District data are scheduled for 1993.

Short-form characteristics data. This expanded data concept tabulates some 2,100 cells of short-form information for areas down to the census tract, and with separate summaries by race and Hispanic origin. Geographic data have either an eight-level hierarchy (excluding blocks and block groups) or are inventory-type files (these provide level-wide aggregates, such as totals for all counties).

These computer tapes are called Summary Tape File 2, and include three separate files (STF 2A, B, and C). Data selected from the tapes are also available in printed reports of population and housing characteristics, including race and Hispanic origin. Data in this STF series are not available on compact disc. All tapes and reports are scheduled for release during calendar year 1992.

Long-form data for small areas. This concept features tabulations of over 3,300 cells of information from the forty-five additional long-form population and housing questions for areas as small as one block group. Geographic data are in up to nine-level hierarchical structure (excluding census blocks), and include separate data summarized by five-digit ZIP Code and Congressional District (not available on CD-ROM or microfiche).

Computer tapes with these data are called Summary Tape File 3, and consist of four separate files (STF 3A, B, C, and D). Some tape data are available in printed reports of population, housing, economic and social characteristics, compact discs, and microfiche. The first tape file and reports will be released in 1992, and release of remaining products will continue through 1993.

Long-form detailed characteristics. This concept expands earlier long-form data to tabulate over 5,300 cells of information for areas as small as one census tract (several block groups). Considerably more subject matter detail is provided here than in STF 3. Geographic data are either hierarchically structured or in inventory-type files.

Computer tapes are called Summary Tape File 4, and include three separate files (STF 4A, B, and C). Tape data are included in printed reports of social, economic and housing characteristics, including race, Hispanic origin and ancestry. The first tape files are scheduled for release starting in 1992, with other tapes and printed reports released through 1993.

Public use microdata samples. Rather than detailed data tabulations, the concept here is two computer tape files that contain samples of individual information from long-form census records with all identifying information removed. Geographic detail is sufficiently broad to protect confidentiality. One file provides information for a 5 percent sample of housing units and their occupants for areas of 100,000 or more inhabitants. The second file provides information for a 1 percent national sample, and includes codes to identify metropolitan areas that may cross state boundaries. Both tape files are scheduled for release in calendar year 1993.

Special reports and tape files. This series includes detailed occupational and educational tabulations for places with 50,000 or more inhabitants (the Equal Employment Opportunity Special File), summary statistics for intra- and interstate population movement by county (the County-to-County Migration File), and reports on forty selected population and housing subjects (Subject Summary Tape Files). Tapes contain geographic detail not available in printed reports. The EEO file will be released in 1992,and other products will be available in 1993.

NEW GEOGRAPHIC INFORMATION

An important innovation for the 1990 census is a geographic database called TIGER (Topologically Integrated Geographic Encoding and Referencing). The TIGER System is unique in providing computer-readable geographic information consistent with other 1990 data products down to the block level. It allows users to "piece together" areas for the entire United States and its territories.

The TIGER System is important because it improves census maps, assists in small-area data use, supports noncensus analyses (such as by latitude and longitude), and can be merged with user-supplied data. For example, TIGER has been used successfully with merged information for business and emergency planning, vehicle routing and delivery, and real estate sales purposes.

TIGER was developed in close cooperation with the U.S. Geological Survey (USGS), and based primarily on Census Bureau 1980 and USGS digitized maps. In concept, TIGER information for an area starts with a "connect the dots" map of latitude and longitude coordinates, and then includes the census geographic hierarchy, comparable 1980 census areas, primary features (for example, roads, rivers and political boundaries), and address ranges and ZIP Codes for urban areas.

Persons interested in TIGER extract products should recognize what they are not. Display a 1990 Census TIGER/Line file and all you see are computer codes. Appropriate software is what makes TIGER generate maps, and work with census and other data using "geographic information systems." The Census Bureau does not provide software, but does provide lists of suitable vendors.

ADDITIONAL RESOURCES

This article can be supplemented by ordering The 1990 Census of Population and Housing Users Guide, available in early 1992, and calling Census Bureau, Customer Services, 301-763-4100, for complete data and ordering information.

"Symposium on the Decennial Census, Government Information Quarterly, Vol. 2, No. 4; 1985. A special-issue that reviews decennial census history, program issues, and data uses.

"Two Hundred Years and Counting: The 1990 Census," Population Bulletin, Vol. 44, No. 1; 1989. An overview of 1990 census methods and products, including item-by-item question changes.

1990 Census of Population and Housing, Content Determination Reports, Nos. 1-14, U.S. Census Bureau, 1987-90. Details the development of 1990 census intent and legislative uses of census data.

1990 Census of Population and Housing Tabulation and Publication Program, U.S. Census Bureau, 1989. A compilation of census data products, dissemination media and release schedules.

"Symposium on Geographic Information Systems," Government Information Quarterly, Vol. 7, No. 3, 1990. A review of geographic information systems, including TIGER.

"The TIGER System: Automating the Geographic Structure of the United States Census," Government Publications Review, Vol. 13, 1986. A detailed review of TIGER history and structure.

Printed reports of 1990 census data are sold by mail, telephone and facsimile order by the U.S. Government Printing Office (Washington, DC, 20402; voice phone 202-783-3238, FAX 202-275-0019).

Computer products for the 1990 census are sold by mail, telephone, and facsimile order by the U.S. Census Bureau, Customer Services Office (Washington, DC, 20233; voice phone 301-763-4100, FAX 301-763-4794).
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Author:Ostenso, John
Publication:Business Economics
Date:Oct 1, 1991
Words:1930
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