NCPA - National Center for Policy Analysis


August 6, 2004

Every 10 years, every American household is asked to provide information for the Census. Most households receive the short form, but 20 million are required to respond to a detailed questionnaire, known as the long form. Many people consider one or more of the questions to be intrusive.

Between 1990 and 2000, the return rate for the long form decreased significantly compared to the return rate for the short form; by 2000, the difference between the two return rates had doubled to 9 percent. Moreover, a survey conducted by Knowledge Networks revealed:

  • Although the census is mandatory, 71 percent believe that intrusive questions should not be answered.
  • An additional 13 percent were unsure, while only 16 percent say that an intrusive question should still be answered.

The Census Bureau compensates for the missing data by assigning values -- a process known as imputation. Imputation rates varied widely between the 1990 and 2000 census and depended on the question asked. For example:

  • The imputation rate for "wage and salary income" doubled from 10.0 percent in 1990, to 20.0 percent in 2000.
  • The imputation rate for "age" almost tripled between 1990 and 2000, from .9 percent to 2.6 percent.
  • The imputation rate for "value of property" was 3.3 percent in 1990, but quadrupled to 13.3 percent in 2000.

In an effort to increase cooperation, the long form will be replaced with the American Community Survey (ACS), beginning in 2006. The survey will be given to 250,000 households each month and then summarized across five years. The premise is that a smaller monthly sample will generate less public outcry then the distribution of 20 million forms simultaneously, as occurred in 2000.

Sources: Kenneth Prewitt, "What if We Give a Census and No One Comes?" Science, June 4, 2004. C.F. Citro, D.L. Cork, J.L. Norwood, Eds. "The 2000 Census: Counting Under Adversity," National Academies Press, Washington DC, 2004.

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