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This document was downloaded
and archived from http://www.census.gov/acs/www/index_a.htm
on May 19, 2001. |
The decennial census has two parts: 1) it counts the population; and 2) for the administration of federal programs and the distribution of billions of federal dollars, it obtains demographic, housing, social, and economic information by asking a 1-in-6 sample of households to fill out a “long form.”
Since this is done only once every 10 years, long-form information becomes out of date. Planners and other data users are reluctant to rely on it for decisions that are expensive and affect the quality of life of thousands of people. The American Community Survey is a way to provide the data communities need every year instead of once in ten years. It is an on-going survey that the Census Bureau plans will replace the long form in the 2010 Census.
Full implementation of the survey would begin in 2003 in every county of the United States. The survey would include three million households. Data are collected by mail and Census Bureau staff follow up those who do not respond.
The American Community Survey will provide estimates of demographic, housing, social, and economic characteristics every year for all states, as well as for all cities, counties, metropolitan areas, and population groups of 65,000 people or more.
For smaller areas, it will take three to five years to accumulate sufficient sample to produce data for areas as small as census tracts. For example, areas of 20,000 to 65,000 can use data averaged over three years. For rural areas and city neighborhoods or population groups of less than 20,000 people, it will take five years to accumulate a sample that is similar to that of the decennial census. These averages can be updated every year, so that eventually, we will be able to measure changes over time for small areas and population groups.
The American Community Survey can identify changes in an area's population and give an up-to-date statistical picture when data users need it, every year, not just once in ten years. Communities can use the data, to track the well-being of children, families, and the elderly; determine where to locate new highways, schools, and hospitals; show a large corporation that a town has the workforce the company needs; evaluate programs such as welfare and workforce diversification; and monitor and publicize the results of their programs.
The American Community Survey is conducted using the best mail self-response techniques of the decennial census combined with follow-up techniques that produce high-quality data. For households that do not respond by mail, the quality of data is improved by using well-trained, permanent interviewer staff using computerized interviewing, which incorporates edits into the collection process. Using a permanent coding staff provides additional improvements in data quality.
As an on-going survey, the American Community Survey is a flexible vehicle, capable of adapting to changing customer needs. Once it is fully implemented, the potential is there to add questions of national policy interest or specialized supplements to help identify the situations of special population groups.
The MAF can be created automatically for all areas that have city-style address systems where the mail is delivered using these addresses. For areas that do not have a city-style address system, the Census Bureau creates a MAF by conducting an address listing operation.
The MAF will be used as a sampling frame for the American Community Survey, as well as all of the Census Bureau's demographic surveys.
A critical element in the overall success of the ACS is the ability to keep the Census Bureau's MAF up-to-date and accurate from year to year, especially in rural areas. The MAF serves as the main source of the housing unit sample for the ACS. In addition, the housing unit counts contained in the MAF play an important part in the editing, weighting, and data tabulation process. Thus, the overall accuracy of the MAF is a paramount concern.
The need for an up-to-date MAF spawned the development of a new program called the American Community Survey - Coverage Program (formerly called the Community Address Updating System). This program, which is currently under development, has two major objectives:
A larger proportion of addresses will be sampled for small governmental units (American Indian reservations, counties, and towns). The monthly sample size is designed to approximate the sampling ratio of Census 2000, including the oversampling of small governmental units.
Self-enumeration through mail-out/mail-back methodology--The self-enumeration procedure uses several mailing pieces: a prenotice letter, the American Community Survey questionnaire, and a reminder card. A replacement questionnaire will be mailed to addresses in the sample if the original questionnaire is not completed and returned to the processing office within the prescribed amount of time. Sample addresses that do not respond by mail will be contacted using the follow-up procedures CATI, CAPI, or both.
Computer Assisted Telephone Interviewing (CATI)--The CATI operation is conducted approximately six weeks after the American Community Survey questionnaire is mailed. We will attempt to obtain telephone numbers and conduct telephone interviews for all households that do not respond by mail. Census Bureau telephone interviewing staff will conduct these interviews.
Computer Assisted Personal Interviewing (CAPI)--Following the CATI operation, a sample will be taken from the addresses which remain uninterviewed. These addresses will be visited by Census Bureau field representatives, who will conduct personal interviews to obtain the information on the American Community Survey.
In 1999, the number of sites in the sample increased to 31 comparison sites. The comparison with Census 2000 is designed to collect several kinds of information necessary to understand the differences between 1999-2001 American Community Survey and the 2000 long form.
The comparison sites include various situations in which these differences are expected to be prominent. They were selected to have at least one site in each of 24 strata representing combinations of county population size, difficulty of enumeration, and 1990-1995 population growth. The selection also attempts to balance areas by region of the country, and seeks to include several sites representing different characteristics of interest, such as racial or ethnic groups, highly seasonal populations, migrant workers, American Indian reservations, improving or worsening economic conditions, and predominant occupation or industry types.
The purpose of the comparison sites is to give a good tract-by-tract comparison between the 1999-2001 American Community Survey cumulated estimates and the Census 2000 long-form estimates, and to use these comparisons to identify both the causes of differences and diagnostic variables that tend to predict a certain kind of difference.
In 2002, we will continue to collect data in the 31 comparison sites to maintain the continuity of the survey.
In 2003, plans are to implement the American Community Survey in every county of the United States with an annual sample of three million housing units. Once the survey is in full operation, American Community Survey data will be available every year for areas and population groups of 65,000 or more beginning in 2004.
For small areas and population groups of 20,000 or less, it will take five years to accumulate a large enough sample to provide estimates with accuracy similar to the decennial census. That means updated information for areas such as neighborhoods will be available starting in 2008 and every year thereafter.
Plans include the release of a microdata file each year patterned after the five percent Public Use Microdata Sample (PUMS) file of the 1990 decennial census records. The microdata file allows for two different units of analysis: housing unit and person. The microdata file includes as many records as possible and shows the lowest level of geography possible within confidentiality constraints. Users of the American Community Survey data can customize tabulations to examine the information in the way that best serves their needs.
In addition, the American Community Survey will provide summarized data for population and housing estimates, cross tabulated by various characteristics, down to the block-group level. The summarized data will be similar to the Summary Tape Files (STF) of the 1990 decennial census records, and are designed to provide statistics with greater subject and geographic detail than is feasible or desirable to provide in printed reports.
The microdata files, tabulated files, and associated documentation will be available on CD-ROM, as well as on this web site.
The American Community Survey can screen for households with specific characteristics. These households could be identified through the basic survey, or through the use of supplemental questions. Targeted households can then be candidates for follow-up interviews, thus providing a more robust sampling frame for other surveys. Moreover, the prohibitively expensive screening interviews now required would no longer be necessary.
State and local governments are becoming more involved in administering and evaluating programs traditionally controlled by the federal government. This devolution of responsibility is often accompanied by federal funding through block grants. The data collected via the American Community Survey will be useful not only to the federal agencies, but also to state, local, and tribal governments in planning, administering, and evaluating programs.
Finally, the American Community Survey will provide more timely data
for use in area estimation models that provide estimates of various concepts
for small geographic areas. In essence, detailed data from national household
surveys (whose samples are too small to provide reliable estimates for
states or localities) can be combined with data from the American Community
Survey to create reliable estimates for small geographic areas.
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