Comparing American Community Survey Data Over Time
-- focus on comparing ACS 5-year estimates: 2005-2009 with 2010-2014
To make good business decisions we need hard data, recent data, trend data ... to assess patterns and change and develop reliable, superior plans. Read about the past and then how things have changed for the better.
Imagine that it is 2005. Data from Census 2000 are now 5 years old. There will not be another update for richer demographics for all counties and cities in the foreseeable further. There will not be any update for small area geography such as census tracts or block groups until Census 2010. Businesses are forced to use out-of-date data to assess markets ... where and how are opportunities changing? City and neighborhood planners can only make educated guesses to respond to growing needs of various population groups. Federal and state government programs that base funding allocations on demographics are challenged. Changes in the rental vacancy rates for most cities, counties and metros will remain unknown for the foreseeable future.
Fast forward to 2015 and present day reality. The situation is now radically different. First, we can now compare 5-year estimates from the 2009 American Community Survey ACS to those from the 2014 ACS 5 year estimates. Second, we will be able to do that again in 2016 -- compare 5-year estimates from ACS 2010 to those from ACS 2015. Health planners can now assess the size and change in special needs population and how that matches up to resources that respond to those needs -- rather than guessing. Schools and school districts can better understand how school age population trending and plan for enrollment change. Education agencies are better able to assess how changing demographics among school systems compare to one-another. Businesses can now determine the size of potential markets and how they are trending based on hard data. It is possible to compare changing patterns in rental vacancy rates and rental housing market conditions for all levels of geography down to block group.
The American Community Survey ACS provides a wide range of important statistics about people and housing for every community in the nation. These data are the only source of local estimates for most of the approximately 40 topics it covers for even the smallest communities. It produces statistics for ancestry, language, education, commuting, employment, mortgage status and rent, as well as income, poverty and health insurance. The ACS estimates are tabulated annually as 1-year estimates (e.g., the ACS 2014 1-year estimates) and 5-year estimates (e.g., the ACS 2014 5-year estimates. See a comparison below in this section about scope, advantages/disadvantages, and other usage attributes for the 1-year versus 5-year estimates.
See ACS 2014 5-year main page for additional data access & use details.
Data from the 5-year estimates are available for all geographies down to the block group level regardless of population size. Starting with the ACS 2014 5-year estimates, for the first time, users will be able to compare two non-overlapping five-year periods 2005-09 and 2010-14. Looking ahead, data from the 2006-10 and 2011-15 (available December 2016) will be comparable ... and so on. Over several years, a time-series of 5-year estimates, non-overlapping five-year periods, will evolve.
Comparing Geography Between the 2005-09 and 2010-14 ACS 5-Year Data
Use links in the right column to access data for the specified geography. Note that the underlying tabulation area geography differs for various types of areas. Starting with the ACS 2006-10 5-year estimates, most Census 2000 based geography shifts to Census 2010, making for systemic comparison of "apples-to-apples." This table will update with more detail, including data access links, and as new data become available. See notes on keeping up-to-date below the table.
Using links in table: some links in table are explanatory only;
- those with words "click to open ..." in hover text will open the described page in a new window
Counts of tabulation areas, for selected geographies, show in column 2 following ":".
Jan 1, 2013 and Jan 1, 2009 reflect geography vintages based on annual Census Boundary Annexation Survey.
For "Legal Areas> county or equivalent" -- U.S. only (states and D.C.), Jan 1, 2013 count = 3,142.
ZIP Code Tabulation Areas were introduced with release of the ACS 2011 (2007-2011 5 year).
Definitions of metros differ substantially between the Feb 28, 2013 vintage and the Nov 1, 2008 vintage.
- the Feb 28, 2013 vintage remains the current (as of 11/15) vintage in use for all Federal statistical programs.
- use county level data from ACS 2005-09 to aggregate to Feb 28, 2013 vintage for geographic comparability
Census 2010 Public Use Microdata Areas (PUMAs) introduced with release of ACS 2012 (2008-2012 5 year data).
- Census 2010 vintage PUMA geography differs substantially from Census 2000 vintage PUMAs.
- as PUMAs are areas of 100,000 population and over, the ACS 1-year estimates may be preferred.
- PUMA ACS 1-year estimates offer a mini time-series: 2012, 2013, 2014.
Keeping up-to-date [top]
While the ACS data can be used very effectively alone, without integration with other data, the real power and opportunity comes from combined the ACS-sourced data with other data. ProximityOne progressively updates users/clients as new and related data and data analytics opportunities become available.
Updates are sent to ProximityOne User Group members (join here).
ACS updates and applications are covered in the Data Analytics Blog.
ACS data access, integration & use ... join us in a Data Analytics Lab session.
Comparing ACS 1-Year versus ACS 5-Year Data [top]
Advantages of using the 5-year estimates
The data are available for all census tracts, ZIP codes and block group areas.
The data are available for all cities/places, counties and school districts irrespective of size.
Disadvantages of using the 5-year estimates
The data are older than the 1-year estimates.
The data are for a multi-year period rather than one year.
Additional cautions in comparing estimates over time (see below).
Advantages of using the 1-year estimates
The data are more recent than the 5-year estimates.
The data are generally more accurate than the 5-year estimates.
Disadvantages of using the 5-year estimates
The data are not available for census tracts and ZIP code areas.
The data are available for only areas of 65,000 population and over.
The margin of error (MOE) of the estimate is normally larger that for the 5-year estimates.
Additional cautions in comparing estimates over time
ACS 2009 5 year estimates are based on survey respondent data during the years 2005 through 2009.
... note that more than half of responses are from pre-recession period
... household income, value, employment, etc. will not be "even" over 5 year period.
ACS 2014 5 year estimates are based on survey respondent data during the years 2010 through 2014.
ACS 2009 compared to ACS 2014 5 year estimates use differently sourced tabulation area geography.
... in many cases there is no difference ... in other cases the difference is nominal
... and in yet other cases there are workarounds (e.g., aggregating county data to current definition metros).
The ACS 2013 5 year estimates and ACS 2014 5 year estimates
include the same respondent data for the years 2010 though 2013.
The ACS 2014 5 year estimates are "refreshed" by dropping
the 2009 respondents and adding the 2014 respondents.
While the estimates are independently developed,
they include demographic-economic characteristics for some of the same respondents.
Support Using these Resources
Learn more about accessing and using demographic-economic data and related analytical tools. Join us in a Data Analytics Lab session. There is no fee for these one-hour Web sessions. Each informal session is focused on a specific topic. The open structure also provides for Q&A and discussion of application issues of interest to participants.
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ProximityOne develops geodemographic-economic data and analytical tools and helps organizations knit together and use diverse data in a decision-making and analytical framework. We develop custom demographic/economic estimates and projections, develop geographic and geocoded address files, and assist with impact and geospatial analyses. Wide-ranging organizations use our tools (software, data, methodologies) to analyze their own data integrated with other data. Follow ProximityOne on Twitter at www.twitter.com/proximityone. Contact us (888-364-7656) with questions about data covered in this section or to discuss custom estimates, projections or analyses for your areas of interest.