U.S. flag

An official website of the United States government

Skip Header


Comparing 2006-2010 ACS 5-year and 2011-2015 ACS 5-year

When comparing the 2006-2010 ACS 5-year estimates with the 2011-2015 ACS 5-year estimates, there are several issues to consider:

  1. Change in geographic boundaries - The 2006-2010 ACS 5-year estimates used legal boundaries as of January 1, 2010. The 2011-2015 ACS 5-year estimates use legal boundaries as of January 1, 2015. Most statistical areas for both datasets use 2010 Census vintage geographies. For more information on geographic concepts used in the ACS, visit Geography and the ACS.
  2. Change in the questionnaire or coding - The list below provides details by subject for major questionnaire or coding changes.

The ACS question on race was revised in 2008 to make it consistent with the 2010 Census race question. For more information, see the questionnaire changes document. The reporting of "Other Asian" groups (e.g., Pakistani), "Other Pacific Islander" groups (e.g., Fijian), and the reporting of "White" responses increased at the national level, and the reporting of "Some Other Race" responses decreased at the national level. The change in estimates from 2007 to 2008 may be due to several factors including questionnaire changes, population controls, and methodological changes to the population estimates, and therefore should be used with caution.  Due to these changes, use caution when comparing 2011-2015 ACS 5-year estimates with 2006-2010 ACS 5-year estimates.

Top of Section

The ACS question on Hispanic origin was revised in 2008 to make it consistent with the 2010 Census Hispanic origin question. For more information, see the questionnaire changes document. The reporting of specific Hispanic groups (e.g., Colombian, Dominican, Spaniard, etc.) increased at the national level. The change in estimates from 2007 to 2008 may be due to several factors including questionnaire changes, population controls, and methodological changes to the population estimates, and therefore should be used with caution. Due to these changes, caution is suggested when comparing 2011-2015 ACS 5-year estimates with 2006-2010 ACS 5-year estimates.  For more information about the changes in the estimates, visit "Changes to the American Community Survey Between 2007 and 2008 and Their Potential Effect on the Estimates of Hispanic Origin Type, Nativity, Race, and Language" [PDF - <1.0 MB].

Top of Section

Data from 2011-2015 are comparable to 2006-2010 as long as some caution is used. In 2010, there were two major changes to the coding rules. If up to two ancestries were listed, both were coded, even if one was the specific of the other or if one was American. Also, race groups and Hispanic groups were coded with the same priority as non-race and non-Hispanic groups. For example, "Haitian Black French" would previously have been coded Haitian and French, but now would be coded Haitian and Black. Beginning with the 2008 ACS 1-year data products, people who reported Irish-Scotch ancestry were classified under "Other groups", whereas in the 2007 ACS and earlier they were classified as Scotch-Irish. Due to this classification change, the Scotch-Irish category decreased from 2007-2008.

Top of Section

Modest changes were made in 2009 to the region and country groupings. Specifically, Macau (code 225) is now included under the definition of China, and Jan Mayen (code 121) and Svalbard (code 135) are included under the definition of Norway, please see 2009 ACS Code List.  These changes do not limit comparing most 2006-2010 ACS 5-year and 2011-2015 ACS 5-year estimates.

Top of Section

Beginning with the 2008 ACS, the migration section of the questionnaire was expanded to collect street address information for residence 1 year ago. The additional detail improves the accuracy of coding and updating residence 1 year ago to current geographical boundaries, which may affect the estimates for movers within the same city/town and movers from principal cities. Areas with recent boundary changes, vague boundaries, or duplicate names are most likely affected. For more information see the report titled Report P.3: Evaluation Report Covering Residence 1 Year Ago (Migration).  These changes do not limit comparing most 2006-2010 ACS 5-year and 2011-2015 ACS 5-year estimates.

Top of Section

The "Child" and "In-law" categories were expanded in the 2008 ACS questionnaire. When comparing 2006-2010 to 2011-2015, use caution when comparing these categories.  See "Changes in the Relationship Categories Between 2007 and 2008" [PDF - <1.0 MB] for more information on category changes and comparisons. Changes in the questionnaire format and data capture procedures between 2007 and 2008 have resulted in changes in the total number of same-sex unmarried partners in 2008. For more information about same-sex unmarried partners, visit "Changes to the American Community Survey Between 2007 and 2008 and Their Potential Effect on the Estimates of Same-Sex Couple Households" [PDF - <1.0 MB].  Due to these differences, use caution when comparing 2006-2010 to 2011-2015 same-sex unmarried partner data.

Top of Section

Changes in the questionnaire format and data capture procedures between the 2007 and 2008 ACS have resulted in changes in the number of reported same-sex spouses and hence the total number of same-sex unmarried partners in 2008. All same-sex-unmarried-partner comparisons between 2006-2010 and 2011-2015 should be made with caution due to these formatting and data capture changes.  For more information about same-sex unmarried partners, visit "Changes to the American Community Survey Between 2007 and 2008 and Their Potential Effect on the Estimates of Same-Sex Couple Households" [PDF - <1.0 MB].

Top of Section

New questions were added to the 2008 ACS CATI/CAPI instrument. Respondents who received a high school diploma, GED or equivalent were also asked if they had completed any college credit. Therefore, data users may notice a decrease in the number of high school graduates relative to previous years because those people are now being captured in the "Some college credit, but less than 1 year of college credit" or "1 or more years of college credit, no degree" categories. Because of these changes, caution should be used when comparing the 2006-2010 and 2011-2015 datasets.  For more information see the report titled Report P.2.b: Evaluation Report Covering Educational Attainment.

Top of Section

Use caution when making comparisons between the 2006-2010 ACS 5-year estimates and 2011-2015 ACS 5-year estimates of spoken languages and English-speaking ability.  Changes to collection of data on Hispanic origin may have affected some language characteristics. The observed increase in the native Hispanic population speaking English "very well" is larger than anticipated and should be interpreted with caution. In some cases the overall English language ability in the population may have been affected. See the section on Hispanic Origin (03) above for more information. For more information about the changes in the estimates, visit "Changes to the American Community Survey Between 2007 and 2008 and Their Potential Effect on the Estimates of Hispanic Origin Type, Nativity, Race, and Language" [PDF - <1.0 MB].

Top of Section

The 2008 ACS disability questions are different from the 2007 and prior ACS disability questions, thus 2006-2010 comparisons cannot be made to 2011-2015 data.  The 2008 ACS disability questions are also different from the Census 2000 and prior disability questions, thus a comparison cannot be made. For information about definitions of disability in the ACS, Census 2000 and other Census Bureau surveys, visit the Disability website.

Top of Section

Income and earnings estimates in the 2006-2010 ACS 5-year data set are inflation-adjusted to 2010 dollars.  Income and earnings estimates in the 2011-2015 ACS 5-year data set are inflation-adjusted to 2015 dollars.  To compare income estimates between the two, multiply the 2006-2010 dollar estimates by 1.08710584 (CPI-U-RS) in order to inflation-adjust  2010 dollars to 2015 dollars. The exception is the Comparative Economic Characteristics Profile (CP03) where all income and earnings dollar values are presented in 2015 inflation-adjusted dollars. Note that the Census Bureau inflation-adjusts microdata to arrive at the adjusted dollar values in CP03.  Data users will not be able to exactly replicate the CP03 2006-2010 inflation-adjusted values.

Top of Section

Income and earnings estimates in the 2006-2010 ACS 5-year data set are inflation-adjusted to 2010 dollars.  Income and earnings estimates in the 2011-2015 ACS 5-year data set are inflation-adjusted to 2015 dollars.  To compare income estimates between the two, multiply the 2006-2010 dollar estimates by 1.08710584 (CPI-U-RS) in order to inflation-adjust 2010 dollars to 2015 dollars. The exception is the Comparative Economic Characteristics Profile (CP03) where all income and earnings dollar values are presented in 2015 inflation-adjusted dollars. Note that the Census Bureau inflation-adjusts microdata to arrive at the adjusted dollar values in CP03.  Data users will not be able to exactly replicate the CP03 2006-2010 inflation-adjusted values.

Top of Section

In 2013, the veteran status question was modified. Accordingly, we recommend using caution when making comparisons of the estimate of the veteran population from the 2006-2010 ACS 5-year with the 2011-2015 ACS 5-year. For more information, visit the Veterans Statistics webpage.

In 2008, a new question was added to the ACS to collect information on service-connected disability status and ratings. Consequently, comparisons are not available for this topic between the 2006-2010 ACS 5-year and the 2011-2015 ACS 5-year.  For more information, visit the Veterans Statistics webpage.

Top of Section

In 2010, we added an instruction to the food stamp question incorporating the new program name - Supplemental Nutrition Assistance Program (SNAP). The wording of the food stamp question was revised in the 2008 ACS to ask respondents if they received "food stamps or a food stamp benefit card."  Data users may see an increase in food stamp recipiency from the 2007 ACS 1-year estimates to the 2008 ACS 1-year estimates as a result of the questionnaire change. For more detailed information, see the Evaluation Report Covering Receipt of Food Stamps.  These changes do not limit comparing most 2006-2010 ACS 5-year and 2011-2015 ACS 5-year estimates.

Top of Section

The Census Bureau introduced an improved sequence of labor force questions in the 2008 ACS questionnaire. Accordingly, we recommend using caution when making labor force data comparisons between the 2006-2010 ACS 5-year and 2011-2015 ACS 5-year. For more information on these questions and their evaluation in the 2006 ACS Content Test, see the Evaluation Report Covering Employment Status and the Evaluation Report Covering Weeks Worked. Additional information can also be found on the Labor Force Statistics website.

Top of Section

The 2006 to 2007 ACS industry data are coded using the 2002 North American Industry Classification System (NAICS).  The 2008 to 2012  ACS industry data use the 2007 NAICS codes. The 2006-2010 multiyear industry data was recoded using 2007 NAICS codes.

The ACS industry data for 2013 and later years are based on the 2012 revision of the NAICS codes. To allow for the creation of the 2011-2015 tables, industry data in the 2011-2015 multiyear file were recoded to 2013 Census industry codes. Because of the Census industry code changes, we recommend using caution when comparing 2011-2015 industry data with 2006-2010 industry data. For more information on Census industry code changes, please visit the Industry and Occupation website.

The Census occupation codes for 2010 and later years are based on the 2010 revision of the Standard Occupational Classification (SOC). To allow for the creation of 2006-2010 tables, occupation data in the 2006-2010 multiyear file was recoded to 2010 Census occupation codes. The 2006-2010 and 2011-2015 occupation codes are both based on 2010 revision of the SOC, and therefore are comparable. For more information on the Census occupation code changes, please visit Industry and Occupation website.

Top of Section

Caution should be used when comparing data for bedrooms between the 2007 and 2008 ACS.  This would include any multiyear (3-year, 5-year) comparisons that include the pre-2008 bedrooms data.  For instance, caution should be used when comparing the 2006-2010 and 2011-2015 ACS 5-year datasets.  Changes made to the 2008 ACS bedrooms question involving the wording as well as the response option resulted in a noticeable increase in the "No bedroom" category and a decrease in the "1 bedroom" to "3 bedrooms" categories. For more detailed information about these changes, see the Bedrooms section of the Subject Definitions.

Top of Section

Caution should be used when comparing data for kitchen facilities in certain areas between the 2007 and 2008 ACS. This would include any multiyear (3-year, 5-year) comparisons that include the pre-2008 kitchen facilities data.  For instance, caution should be used when comparing the 2006-2010 and 2011-2015 ACS 5-year datasets.  Changes made to the 2008 ACS question wording and translation to the Spanish questionnaire resulted in an inconsistency in the data. For more detailed information about these changes, see the kitchen facilities section of the Subject Definitions.

Top of Section

Caution should be used when comparing data for telephone service availability between the 2007 ACS and the 2008 ACS. This would include any multiyear (3-year, 5-year) comparisons that include the pre-2008 telephone service data.  For instance, caution should be used when comparing the 2006-2010 and 2011-2015 ACS 5-year datasets.  Changes made to the 2008 ACS Telephone Service Availability question involving the structure of the question as well as including an instruction to include cell phones resulted in a noticeable increase in respondents answering "yes" to the question. For more detailed information about these changes, see the telephone service available section of the Subject Definitions.

Top of Section

Caution should be used when comparing data for occupants per room between the 2007 and 2008 ACS. This would include any multiyear (3-year, 5-year) comparisons that include the pre-2008 rooms data.  For instance, caution should be used when comparing the 2006-2010 and 2011-2015 ACS 5-year datasets.  Changes made to the 2008 ACS rooms question involving the wording as well as the response option resulted in a noticeable increase in the "1 room" category and a decrease in the "2 rooms" to "6 rooms" categories. For more detailed information about these changes, see the Rooms section of the Subject Definitions.

Top of Section

Caution should be used when comparing data for plumbing facilities in certain areas between the 2007 and 2008 ACS.  This would include any multiyear (3-year, 5-year) comparisons that include the pre-2008 plumbing facilities data.  For instance, caution should be used when comparing the 2006-2010 and 2011-2015 ACS 5-year datasets.  Changes made to the 2008 ACS question wording and translation to the Spanish questionnaire resulted in an inconsistency in the data. For more detailed information about these changes, see the plumbing facilities section of the Subject Definitions.

Top of Section

Changes made to the value question between the 2007 and 2008 ACS may result in an inconsistency in the value distribution for some areas. This would include any multiyear (3-year, 5-year) comparisons that include the pre-2008 value data.  For instance, caution should be used when comparing the 2006-2010 and 2011-2015 ACS 5-year datasets.  In 2008, the response option for the value question was a write-in. In 2007 and previous years, the value question included categorical response options with a write-in for values over $250,000. The presentation of the data is consistent between 2007 and 2008. For more information about this questionnaire change, see the Evaluation Report Covering Property Value.

Top of Section

Data was not available prior to 2008.  Therefore, the 2006-2010 ACS 5-year estimates were not available.  For more information about health insurance questions in the ACS and other Census Bureau surveys, visit the Health Insurance website.

Top of Section
Page Last Revised - October 8, 2021
Is this page helpful?
Thumbs Up Image Yes Thumbs Down Image No
NO THANKS
255 characters maximum 255 characters maximum reached
Thank you for your feedback.
Comments or suggestions?

Top

Back to Header