Documentation:  ACS 2010 (1Year Estimates) 
you are here:
choose a survey
survey
document
chapter
Publisher: U.S. Census Bureau
Survey: ACS 2010 (1Year Estimates)
Document:  ACS 20101yr Summary File: Technical Documentation 
citation:  Social Explorer; U.S. Census Bureau; American Community Survey 2010 Summary File: Technical Documentation. 
Chapter Contents
The Census Bureau publishes data for 1year, 3year, and 5year estimates, with population thresholds set for the 1year and 3year estimates to produce reliable data. Here is a brief comparison of the three types of estimates:
For more information on the ACS estimates, users are encouraged to visit the ACS website www.census.gov/acs/www/guidance_for_data_users/estimates/.
1Year Estimates  3Year Estimates  5Year Estimates 
Published for selected geographic areas with populations of 65,000 or greater  Published for selected geographic areas with populations of 20,000 or greater 
No population thresholdand published for small geographic areas

Represent the average characteristics over a calendar year  Represent the average characteristics over the 3year period of time  Represent the average characteristics over the 5year period of time 
Have fewer published geographic areas than the 3year and 5year estimates  Have fewer published geographic areas than the 1year estimates but less than the 5year estimates  Have more published areas than the 1year and 3year estimates 
1year estimates  3year estimates  5year estimates 
12 months of collected data  36 months of collected data  60 months of collected data 
Data for areas with populations of 65,000+  Data for areas with populations of 20,000+  Data for all areas 
Smallest sample size  Larger sample size than 1year  Largest sample size 
Less reliable than 3year or 5year  More reliable than 1year; less reliable than 5year  Most reliable 
Most current data  Less current than 1year estimates; more current than 5year  Least current 
Best used when  Best used when  Best used when 
Currency is more important than precision Analyzing large populations 
More precise than 1year, more current than 5year Analyzing smaller populations Examining smaller geographies because 1year estimates are not available 
Precision is more important than currency Analyzing very small populations Examining tracts and other smaller geographies because 1year estimates are not available 
For more information on the ACS estimates, users are encouraged to visit the ACS website www.census.gov/acs/www/guidance_for_data_users/estimates/.
For data quality and geographic reasons, some tables are published with specific geography restrictions. For example, the able B05001PR, Citizenship Status in Puerto Rico, is produced for Puerto Rico only, and the table B08501, Means Of Transportation To Work By Age For Workplace Geography, is only produced for the work place geographies. Appendix E has a complete list of tables and their geography restrictions, and Appendix F has a complete list of ACS 1year published summary levels and components. Other examples include the quality measures tables (the B98 series) and detailed occupation tables.
Some data values represent unique situations where either the information to be conveyed is an explanation for the absence of data, represented by a symbol in the data display, such as "(X)", or the information to be conveyed is an openended distribution, such as 115 or greater, represented by 115+.
The following special data values can appear in the ACS Summary File table as an explanation for the absence of data:
Jam Values for Medians
The following is a listing of the jam values for medians. For example, if there is an estimate of "2499" for table B10010, then it does not indicate a dollar amount. It means that the median is somewhere below 2,500 and thus isn't calculated.
The following special data values can appear in the ACS Summary File table as an explanation for the absence of data:
 Missing Value = ""
 Dot = "."
 Zero = "0"
 Negative 1 = "1"
Jam Values for Medians
The following is a listing of the jam values for medians. For example, if there is an estimate of "2499" for table B10010, then it does not indicate a dollar amount. It means that the median is somewhere below 2,500 and thus isn't calculated.
Jam Value  Actual Meaning  Use for Medians 
0  1 or less  Age, Duration of Marriage 
9  9.0 or more  Rooms 
10  10.0 or less  Gross Rent as Percentage of Income, Owner Costs as Percentage of Income 
50  50.0 or more  Gross Rent as Percentage of Income, Owner Costs as Percentage of Income 
99  100 or less  Rent, Gross Rent, Selected Monthly Owner Costs, Monthly Housing Costs 
101  101 or more  Duration of Marriage 
116  115 or more  Age 
199  200 or less  Tax 
1001  1,000 or more  Selected Monthly Owner Costs 
1939  1939 or earlier  Year Built 
1969  1969 or earlier  Year Moved In 
2001  2,000 or more  Rent, Gross Rent 
2005  2005 or later  Year Built, Year Moved In 
2499  2,500 or less  Income, Earnings 
4001  4,000 or more  Selected Monthly Owner Costs, Monthly Housing Costs 
9999  10,000 or less  Value 
10001  10,000 or more  Tax 
200001  200,000 or more  Income 
250001  250,000 or more  Income, Earnings 
1000001  1,000,000 or more  Value 
B00001, B00002, B98001, and B98002 are sample counts, not estimates, and do not have margin of error (MOE) associated with them. Tables in series B99* imputation tables and B98* (except B98001 and B98002) quality measure tables do not provide margin of error calculations. The margin of error calculations are set to 1 for these tables.
There are a few special rules on how certain margin of error are determined for ACS estimates. The accuracy of the estimate (decimal place) within the detailed tables determines how many digits the margin of error is rounded.
The only exceptions to these rules are tables B19082 (Shares of aggregate household income by quintile) and B19083 (index of income inequality, commonly known as GINI). B19082 has estimates rounded to one decimal place and MOE rounded to two decimal places. B19083 has estimates rounded to three decimal places and MOE rounded to four decimal places.
There are a few special rules on how certain margin of error are determined for ACS estimates. The accuracy of the estimate (decimal place) within the detailed tables determines how many digits the margin of error is rounded.
The only exceptions to these rules are tables B19082 (Shares of aggregate household income by quintile) and B19083 (index of income inequality, commonly known as GINI). B19082 has estimates rounded to one decimal place and MOE rounded to two decimal places. B19083 has estimates rounded to three decimal places and MOE rounded to four decimal places.
Filtering rules, based on statistical reliability of the survey estimates, are used because certain geographic areas contain detailed tables include estimates whose level of reliability is unacceptable. The data release rules for the American Community Survey data tables include the following.
Every base table consists of a series of estimates. If more than half the estimates are not statistically different from 0 (at a 90 percent confidence level), then the table fails. Each estimate is subject to sampling variability that is summarized by its standard error. Dividing the standard error by the estimate yields the coefficient of variation (CV) for each of the estimates. (If the estimate is 0, a CV of 100 percent is assigned.) To implement this requirement for each table at a given geographic area, CVs are calculated for each of the table's estimates, and the median CV value is determined. If the median CV value for the table is less than or equal to 61 percent, the table passes for that geographic area; if it is greater than 61 percent, the table fails. Tables that are too sparse will fail this test. In that case, the table will not be published for that geographic area. Whenever a table fails, a simpler table that collapses some of the detailed lines together can be substituted for the original, more detailed table. The rules are then applied to the simpler table. If it passes, the simpler table is released. If it fails, none of the estimates for that particular table is released for this geographic area. These rules are applied to singleyear period estimates and multiyear period estimates based on three years of sample data.
Every base table consists of a series of estimates. If more than half the estimates are not statistically different from 0 (at a 90 percent confidence level), then the table fails. Each estimate is subject to sampling variability that is summarized by its standard error. Dividing the standard error by the estimate yields the coefficient of variation (CV) for each of the estimates. (If the estimate is 0, a CV of 100 percent is assigned.) To implement this requirement for each table at a given geographic area, CVs are calculated for each of the table's estimates, and the median CV value is determined. If the median CV value for the table is less than or equal to 61 percent, the table passes for that geographic area; if it is greater than 61 percent, the table fails. Tables that are too sparse will fail this test. In that case, the table will not be published for that geographic area. Whenever a table fails, a simpler table that collapses some of the detailed lines together can be substituted for the original, more detailed table. The rules are then applied to the simpler table. If it passes, the simpler table is released. If it fails, none of the estimates for that particular table is released for this geographic area. These rules are applied to singleyear period estimates and multiyear period estimates based on three years of sample data.
The estimates in the summary files are stored using standard notation instead of in scientific notation. The estimates are stored as whole numbers. The largest estimate in a Summary File contains 14 digits.
There are 72 tables that differ between the United States (the 50 states and the District of Columbia) and Puerto Rico. The tables are different because the comparable tables may they contain different metadata (such as C06001 having 45 cells and C06001PR having 37 cells). To identify what tables are available for Puerto Rico only look for the "PR" suffix in the table id (e.g. C06001PR). Because of that, there are sequence files that apply only to the 50 states and the District of Columbia or only to Puerto Rico:
Therefore, for sequences 167179 for areas other than Puerto Rico, the sequence files exist, but they are blank.
US/Stateonly Sequences  Missing PR Data  PR Only Sequences  Missing US/State Data 
1 (US)  169 (PR) 
2 (US)  170 (PR) 
23 (US)  171 (PR) 
24 (US)  172 (PR) 
25 (US)  173 (PR) 
28 (US)  174 (PR) 
29 (US)  175 (PR) 
30 (US)  176 (PR) 
31 (US)  177 (PR) 
32 (US)  178 (PR) 
167(US)  179 (PR) 
Therefore, for sequences 167179 for areas other than Puerto Rico, the sequence files exist, but they are blank.
There are eight tables with more than the maximum 245 cells that cannot fit into a single sequence, so each of these tables is broken into multiple sequence files. The table below shows the tables that contain multiple sequences:
Tables That Are Contained in More Than One Sequence File
The last six tables on the list are only produced at the United States national level (summary level 010), and the files for these sequences will be blank for all other summary levels.
Tables That Are Contained in More Than One Sequence File
Table ID  Table Title  Sequences 
B24010  Sex By Occupation For The Civilian Employed Population 16 Years And Over  107, 108 
B24020  Sex By Occupation For The FullTime, YearRound Civilian Employed Population 16 Years And Over  114, 115 
B24121  Detailed Occupation By Median Earnings In The Past 12 Months For The FullTime, YearRound Civilian Employed Population 16 Years And Over  126, 127, 128 
B24122  Detailed Occupation By Median Earnings In The Past 12 Months For The FullTime, YearRound Civilian Employed Male Population 16 Years And Over  129, 130, 131 
B24123  Detailed Occupation For The FullTime, Year Round Civilian Employed Population 16 Years And Over  132, 133, 134 
B24124  Detailed Occupation For The FullTime, Year Round Civilian Employed Male Population 16 Years And Over  135, 136, 137 
B24125  Detailed Occupation For The FullTime, Year Round Civilian Employed Male Population 16 Years And Over  138, 139, 140 
B24126  Detailed Occupation For The FullTime, Year Round Civilian Employed Female Population 16 Years And Over  141, 142, 143 
The last six tables on the list are only produced at the United States national level (summary level 010), and the files for these sequences will be blank for all other summary levels.