What are the benefits and limitations of using multi-year ACS estimates rather than single year estimates, if both are available?
For places with 65,000 people or more, the American Factfinder currently offers a choice of one-year or three-year estimates. Multi-year estimates from the ACS have the advantage of a larger sample size. However, combining several years may obscure changes in population. One year estimates from the most recently available period are more current and more responsive to changes in population or geographic boundaries. Places smaller than 65,000 people do not have singe year estimates, but depending on size may be limited to multi-year estimates in the Factfinder ACS tables. For more information, see US Census Bureau (2008). Statistical issues of interpretation of the American Community Survey’s one-, three- and five-year period estimates.
