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American Community Survey

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Sample Size and Data Quality

The quality measures provided in this section help the Census Bureau to monitor the accuracy and reliability of American Community Survey (ACS) data, and help to inform the design and methodology of the survey. Use the dropdown menus to explore these measures at the national and state level for the ACS 1-year estimates.

1. How large was the sample used to produce the ACS estimates?

Sample Size:      

Sample Size Definitions

2. How well does the ACS cover the population?

Coverage Rates:      

Coverage Rates Definitions


3. What was the response to the survey?

Response Rates:      

Response Rates Definitions

4. How complete were the data used to produce a specific estimate?

Item Allocation Rates:   

Item Allocation Rates Definitions

You may also access these measures in American FactFinder for the ACS 1-year and 5-year estimates. Some measures are available for counties and places as noted below.

Measures and Table IDs:

  • Sample Size: B98001 (counties for 1-year and 5-year; places for 5-year), B98002
  • Coverage Rate: B98011, B98012, B98013, B98014
  • Response Rate: B98021 (counties for 1-year and 5-year), B98022
  • Item Allocation Rates:

    • B98031 (counties for 5-year), B98032 (counties for 5-year)
    • Some detailed item allocation rates can be calculated using allocation estimates in the B99* series of tables. These tables are available for most published summary levels, for 1-year and 5-year.


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