When to Use 1-year, 3-year, or 5-year Estimates

Choosing which dataset involves more than simply considering the population size in your area. You must think about the balance between currency and sample size/reliability/precision.

For details, research implications, and examples, see "Understanding and Using ACS Single-Year and Multiyear Estimates," page 9 in General Data Users Handbook.

Distinguishing features of ACS 1-year, 1-year supplemental, 3-year, and 5-year estimates

1-year estimates 1-year supplemental estimates 3-year estimates* 5-year estimates
12 months of collected data

Example:

2015 ACS 1-year estimates

Date collected between:

January 1, 2015 and
December 31, 2015

12 months of collected data

Example:

2015 ACS 1-year supplemental estimates

Date collected between:

January 1, 2015 and
December 31, 2015


36 months of collected data

Example:

2011-2013 ACS 3-year estimates

Date collected between:

January 1, 2011 and
December 31, 2013

60 months of collected data

Example:

2011-2015 ACS 5-year estimates

Date collected between:

January 1, 2011 and
December 31, 2015

Data for areas with populations of 65,000+

Data for areas with populations of 20,000+

Data for areas with populations of 20,000+

Data for all areas

Smallest sample size

Smallest sample size

Larger sample size than 1-year

Largest sample size

Less reliable than 3-year or 5-year

Less reliable than 5-year

More reliable than 1-year; less reliable than 5-year

Most reliable

Most current data

Most current data

Less current than 1-year estimates; more current than 5-year

Least current

Annually released:

2005-present

Annually released:

2014-present

Annually released:

2007-2013

Annually released:

2009-present

Best used when Best used when Best used when Best used when

Currency is more important than precision

Analyzing large populations

Currency is more important than precision

Analyzing smaller populations

Examining smaller geographies because the standard 1-year estimates are not available

More precise than 1-year, spans fewer years than 5-year

Analyzing smaller populations

Examining smaller geographies because the standard 1-year estimates are not available

Precision is more important than currency

Analyzing very small populations

Examining tracts and other smaller geographies because 1-year estimates are not available

*ACS 3-year estimates have been discontinued. The 2005-2007, 2006-2008, 2007-2009, 2008-2010, 2009-2011, 2010-2012 and 2011-2013 ACS 3-year estimates will remain available to data users, but no new 3-year estimates will be produced. Every community in the nation will continue to receive a detailed statistical portrait of its social, economic, housing and demographic characteristics through 1-year and 5-year ACS products.