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TextWhich Data Should I Use?
When estimates from Fairfax County and the Census Bureau are compared they often differ. The estimates differ because different methodologies and techniques are used to produce them. Here are some guidelines to help data users decide which data source to use.
Fairfax County
The county produces annual small-area and county-level estimates and forecasts. Point-in-time data as of January 1.
Most reliable when I need:
Decennial Census
Every ten years, the U.S. Census Bureau conducts a complete count of the nation's residents creating small-area and county-level estimates. Point-in-time data as of April 1.
Most reliable when I need:
American Community Survey
Annual survey conducted by the U.S. Census Bureau providing small-area and county-level estimates. Period estimates for one-year, three-year and five-year periods.
Most reliable when I need:
Website Survey 