Documentation: | ACS 2011 (1-Year Estimates) |
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Publisher: U.S. Census Bureau
Survey: ACS 2011 (1-Year Estimates)
Document: | ACS 2011-1yr Summary File: Technical Documentation |
citation: | Social Explorer; U.S. Census Bureau; American Community Survey 2011 Summary File: Technical Documentation. |
Chapter Contents
The American Community Survey (ACS) is a household survey conducted by the U.S. Census Bureau that currently has an annual sample size of about 3.5 million addresses. The ACS produces estimates for numerous social, economic, and housing characteristics, including language, education, commuting, employment, mortgage status, and rent, as well as income, poverty and health insurance. Estimates are available for the nation, all 50 states, the District of Columbia, Puerto Rico, every congressional district, every metropolitan area, and all counties and places with populations of 65,000 or more for the 1-year data release.
Each year the survey produces statistics that cover the periods of 1-year, 3-year, and 5-year estimates for geographic areas in the United States and Puerto Rico, ranging from neighborhoods to Congressional districts to the entire nation. For more information about the ACS, please visit our home page at: http://www.census.gov/acs ACS tables are published on the Census Bureau's American FactFinder (AFF) website, factfinder2.census.gov, and are available for download in several forms. This document will brief data users on the contents of the ACS Summary File and explain how they can use it to obtain the 1-year estimates.
Each year the survey produces statistics that cover the periods of 1-year, 3-year, and 5-year estimates for geographic areas in the United States and Puerto Rico, ranging from neighborhoods to Congressional districts to the entire nation. For more information about the ACS, please visit our home page at: http://www.census.gov/acs ACS tables are published on the Census Bureau's American FactFinder (AFF) website, factfinder2.census.gov, and are available for download in several forms. This document will brief data users on the contents of the ACS Summary File and explain how they can use it to obtain the 1-year estimates.
The American Community Survey Summary File (ACSSF) is a unique data product that includes all the estimates and margins of error from the Detailed Tables and geographies that are published for the ACS. Other ACS data products such as Subject Tables and Data Profiles are created from the Detailed Tables and are therefore not available in the Summary File.
Since the Detailed Tables contain a large number of cells, the tables are stored in a series of files with only the data from the tables, without such information as the title of the tables, the description of the rows, and the names of the geographic areas. That information is in other files that the user must merge with the data files to reproduce the tables.
The ACS Summary File data files are in American Standard Code for Information Interchange (ASCII) format. The files are divided into three types:
Since the Detailed Tables contain a large number of cells, the tables are stored in a series of files with only the data from the tables, without such information as the title of the tables, the description of the rows, and the names of the geographic areas. That information is in other files that the user must merge with the data files to reproduce the tables.
The ACS Summary File data files are in American Standard Code for Information Interchange (ASCII) format. The files are divided into three types:
- Geographies - (position based and comma delimited)
- Estimates - (comma delimited)
- Margins of Error - (comma delimited)
Data contained in the ACS Summary File cover demographic, social, economic, and housing subject areas. All Detailed Tables for the ACS 1-year estimates are in the Summary File and are listed in Appendix E.
The published ACS Summary File geographies cover areas that are based on "summary levels". A summary level specifies the content and the hierarchical relationships of the geographic elements that are required to tabulate and summarize data. For example, summary level code "040" represents the U.S. States, Washington D.C., and Puerto Rico; while summary level code "050" represents counties and county equivalents within states.
In addition to the summary level concept, the ACS 1-year estimates are published for areas that have passed the required 65,000 population threshold.
Many resources are available to help users understand the ACS geographic terms and concepts. For additional information, please visit http://www.census.gov/geo/www/reference.html and http://www.census.gov/acs/www/guidance_for_data_users/geography/. Users may also find the full list of summary levels published for the 1-year Detailed Tables in Appendix F.
The published ACS Summary File geographies cover areas that are based on "summary levels". A summary level specifies the content and the hierarchical relationships of the geographic elements that are required to tabulate and summarize data. For example, summary level code "040" represents the U.S. States, Washington D.C., and Puerto Rico; while summary level code "050" represents counties and county equivalents within states.
In addition to the summary level concept, the ACS 1-year estimates are published for areas that have passed the required 65,000 population threshold.
Many resources are available to help users understand the ACS geographic terms and concepts. For additional information, please visit http://www.census.gov/geo/www/reference.html and http://www.census.gov/acs/www/guidance_for_data_users/geography/. Users may also find the full list of summary levels published for the 1-year Detailed Tables in Appendix F.
Since using the ACS Summary File can be challenging, users should first check if their tables of interest are available for download on American FactFinder. Below are some other options to help users retrieve the tables they want. They are listed in order based on ease of use.
- Summary File Excel Retrieval Tool
- Summary File Excel Import Tool
- SAS Programs
For those who have used the ACS Summary File in previous years, the files for the 1-year estimates are similar to prior publications, with the following exceptions:
- Table Sequencing Now Follows New Rules
- Geographic Area Name Length Increased
Please send any technical questions or comments on the ACS Summary File you have via email to: acso.users.support@census.gov. If you have questions or comments about the American Community Survey, you can submit a question online at www.census.gov.