Variables

American Community Survey 1-, 3-, and 5-Year Estimates

The American Community Survey (ACS) provides four different sets of data tables:

  • Detailed tables. These provide the most detailed set of variables. Table names begin with B followed by a numeric code.

  • Data profile tables. These tables are designed to provide information on a broad array of characteristics for a given geography. There are data profile tables on:

    • Social Characteristics (DP02),
    • Economic Characteristics (DP03),
    • Housing Characteristics (DP04), and
    • Demographic Characteristics (DP05).

    Table names (beginning in DP) are shown in parentheses above.

  • Subject tables. These tables are designed to provide information on narrower topics for a broader range of geographies. Table names begin with S.

  • Comparison profile tables. These tables provide information on changes in characteristics in particular geographies over time, including statistical significance testing. Table names begin with CP.

(Note that this package does not support the new Selected population profile tables for the 1-year estimates.)

The detailed tables are documented in the Summary File Table Shells, available from the ACS Summary File Documentation: https://www.census.gov/programs-surveys/acs/technical-documentation/summary-file-documentation.html This provides data on available variables on a table-by-table basis, and specifies which data releases (1-, 3-, or 5-year estimates) the variable is available for. Each table specifies the universe for which it provides estimates, and includes a total value (denominator) in addition to specific estimates out of that total (numerators). For instance, in the ACS 2015 5-year estimates, table B01001 provides estimates of population by sex and age. The universe for this table is the total population, and variable B01001_001 provides the estimated total. By contrast, a variable like B01001_010 provides the estimated male population aged 22 to 24. To compute the percentage of the population that is male aged 22 to 24, we would divide B01001_010 by B01001_001. It is important to use the denominator from the specific table you are using when performing such computations. While estimates should of the same total should generally be the same across tables, in practice they sometimes differ slightly, so it is important to use consistent values.

Information on the data profile and subject tables is available from https://www.census.gov/acs/www/data/data-tables-and-tools/. Table shells for selected years for the data profile, subject, and comparison profile tables are available from American FactFinder (https://www.census.gov/acs/www/data/data-tables-and-tools/american-factfinder/). Unfortunately, these do not include variable names, unlike the detailed table shells.

Note about annotation fields. The Census has recently updated the API for the ACS 1- and 5-year estimates to include separate annotation fields for each variable. The main data variables (e.g., B01001_001E from the detailed tables) will now contain numeric data exclusively, while any text annotations providing notes about the data will be placed in annotation fields with names ending in ‘A’ (e.g., B01001_001EA). It is important to refer to the annotation fields for relevant notes about the data (e.g., if data are missing due to too few sample observations).

American Community Survey 1-Year Supplemental Estimates

The ACS 1-year supplemental estimates supplement the 1-year estimates by providing estimates for all geographies with a population of 20,000+, as opposed to 65,000+ for the regular 1-year estimates. There are separate tables for the 1-year supplemental estimates. Table names begin with K20. Table shells are available for 2014-2016 under https://www2.census.gov/programs-surveys/acs/tech_docs/table_shells/ Unfortunately, unlike the detailed tables for the regular 1-year estimates, there is no single spreadsheet containing all the table shells.

Census 2010 Summary File 1

Extensive information on the Summary File 1 data is available under https://www.census.gov/newsroom/releases/archives/2010_census/press-kits/summary-file-1.html In particular, the technical documentation, currently available under https://www.census.gov/prod/cen2010/doc/sf1.pdf, provides detailed information on the tables and variables that are available.

Obtaining Information on Variables Through the censusdata package

The censusdata package provides several functions for finding information on tables and variables for these data sets:

  • censustable provides information on entire tables. printtable is also provided to format this information.
  • censusvar provides information on individual variables.
  • search can be used to search for variables based on regular expression matching.