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We measure the state of the nations workforce, including employment and unemployment levels, weeks and hours worked, occupations, and commuting.
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The U.S. Census Bureau is the official source for U.S. export and import statistics and regulations governing the reporting of exports from the U.S.
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The Geographic Support System Initiative will integrate improved address coverage, spatial feature updates, and enhanced quality assessment and measurement.
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Definitions of geographic terms, why geographic areas are defined, and how the Census Bureau defines geographic areas.
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Our researchers explore innovative ways to conduct surveys, increase respondent participation, reduce costs, and improve accuracy.
Our surveys provide periodic and comprehensive statistics about the nation, critical for government programs, policies, and decisionmaking.
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The Census Bureau's Director writes on how we measure America's people, places and economy.
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1. What is item nonresponse?
Missing data for a particular question or item is called item nonresponse. It occurs when a respondent fails to provide an answer to a required item. The ACS also considers invalid answers as item nonresponse.
2. How does the ACS correct for item nonresponse?
The Census Bureau uses imputation methods that either use rules to determine acceptable answers or use answers from similar housing units or people who provided the item information. The first of these two methods is known as assignment, while the second is referred to as allocation.
Assignment involves logical imputation where a response to one question implies the value for a missing response to another question. For example, first name can often be used to assign a value to sex.
Allocation, on the other hand, involves using statistical procedures, such as within-household or nearest neighbor matrices populated by donors, to impute for missing values.
3. Why is it important to measure item nonresponse?
So that data users can judge the completeness of the data in which the survey estimates are based. Final estimates can be adversely impacted when item nonresponse is high and bias can be introduced if the characteristics of the nonrespondents differ from those reported by respondents. Item nonresponse and unit nonresponse both contribute to potential bias in the estimates.
4. How does the ACS measure item nonresponse?
Item nonresponse is measured through the calculation of allocation rates which are published with the survey estimates. The Census Bureau calculates measures of item nonresponse for two distinct universes. The American Factfinder (AFF) includes allocation tables specific to the tabulation universes. This Quality Measures Web page includes allocation rates for the universe that was eligible for editing and imputation. In some instances these will be the same, but in many instances they will differ. For example, we edit and impute data collected for educational attainment for the total population 3 years and over, so that is the universe referenced to calculate the allocation rates shown on the Quality Measures Web page. However, the tables for educational attainment in the AFF are restricted to the population age 25+ and therefore the imputation tables on AFF are restricted to this universe. The specific universe associated with each of these Quality Measures are shown in the tables, displayed below the title of each item.
5. How are item allocation rates calculated?
Allocation rate for item A (state x, year y) =