The ACS in a Nutshell

• The (ACS) is an ongoing survey
  The ACS provides data every year — giving communities the current information they need to plan and to provide services. In addition, survey data help determine how more than $400 billion in federal and state funds are distributed each year.
• Those surveyed include the resident population of the U.S. and Puerto Rico
  This includes all people living in housing units and group quarters. A “group quarters” is a residence that is managed by an organization providing housing or services for residents (e.g. college dormitories, prisons, and nursing homes).
• The survey includes demographic, economic, housing and social characteristics
  The following characteristics are included in the survey: demographic, such as age & sex, race and relationship; economic, such as employment status, poverty, and health insurance coverage; housing, such as occupancy/vacancy status, units in structure and value of home; and social, such as ancestry, citizenship status and marital status. Visit the ACS website for the full list.
• The (ACS) replaced the long form 
  The ACS was distributed for the first time in 2005 and replaced what was once called the “long form.” The long form was completed every 10 years and collected the same information as the short form but also collected more detailed information such as income, education, and language spoken at home. The ACS collects detailed information every year rather than every 10 years. The decennial census is now the short form.
• The ACS is a SURVEY, not a Census
  Unlike the Census 2010, which was filled out by everyone, the American Community Survey is filled out by just a sample of people in each community, and their answers are used to generate estimates that describe the entire community population. To make good estimates about the whole population, a sufficient number of people must be surveyed. For example, the survey responses of one person are not sufficient to make generalizations about even the smallest community in Virginia. Depending on the size of the community, a sample size of 100, 1,000, or even 5,000 people per year may be required.

Survey Basics: Understanding 1-year, 3-year and 5-year estimates

Due to funding constraints, the U.S. Census Bureau has discontinued the 3-year estimates. Visit the U.S. Census Bureau website forrelease dates, and for more information on comparing estimates, and when to use 1-year, 3-year and 5-year estimates

• Sample Size
  • 1-year: all geographic areas
  • 3-year: areas with 20,000 or more
  • 5-year: areas with 65,000 or more
• When to Use 1-year vs. Multi-year (3- or 5-year estimates)
  • Use 1-year estimates when:
    • Currency (timeliness) is critical
    • Researching large areas experiencing rapid change
    • Examining year-to-year changes
  • Use multi-year estimates when:
    • Reliability of the data is critical
    • Analyzing data for small areas (the 1-year sample sizes are too small to get a reliable base for estimates)
    • Studying smaller populations in large areas
    • Examining a set of areas in which some areas have only multi-year estimates
• Comparisons should be made on the same survey year

  ACS estimates based on data collected from 2005–2007 should not be called “2006” or “2007” estimates. Multiyear estimates should be labeled to indicate clearly the full period of time (e.g., “The child poverty rate in 2005–2007 was X percent”).

  The Census Bureau encourages comparing estimates based only on the same survey year(s). For example, suppose someone wanted to compare estimates for the city of Fairfax, which has a population of about 23,000, with estimates for Arlington County, which has a population of over 200,000 people. The ACS publishes 1-year estimates for Arlington County, but only 3-year estimates are currently available for Fairfax City. Thus, you should compare 2005–2007 estimates for Fairfax City with 2005–2007 estimates for Arlington County, even though more recent, single-year estimates are available for Arlington County.

   

• Release Dates New estimates are released every year for both data series. For example:
  • Data released in 2013 includes data collected in 2012 for 1-year estimates and from 2008-2012 for 5-year estimates
  • Data released in 2014 includes data collected in 2013 for 1-year estimates and from 2009-2013 for 5-year estimates

ACS and the Decennial Census