ACS Time Frames
The ACS started in 2005 and is an ongoing survey, releasing products every year as single-year estimates and five-year estimates. ACS single-year estimates are timely, but they are available only for areas with 65,000 residents or more. This is because the ACS is a survey, which means that only a sample and not all Americans respond to the ACS questionnaire. The Census Bureau then uses statistical methods to provide us with representative data about the entire population. In a single year, the Census Bureau collects enough responses that represent large areas well. Still, it cannot collect enough information in each small geography for them to be representative of everyone who lives in that small geography. However, when the Census Bureau combines data over five years, the sample size for these small areas becomes larger. The information is reliable enough that it describes well the population of counties, census tracts, and census block groups. Thus, to get our data on the small geographies we discussed, we will be using the five-year estimates in this tutorial.
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