March 9, 2001
For Immediate Release
Contacts: John Chambers
DESPITE DECLARATIONS OF INCREASED ACCURACY CENSUS 2000 FILLED WITH ERRORS
Errors Match or Exceed 1990 Levels And May Contribute to Reduced Differential Undercount
Washington, D.C. (March 9, 2001) -- After a preliminary analysis of the
Census Bureau's quality control check of the 2000 census, the Accuracy and
Coverage Evaluation (A.C.E.), the Presidential Members of the U.S. Census
Monitoring Board found that the 2000 count contained 44 million errors and
uncertain cases - 9 million more than the 1990 count.
The Census Bureau announced last week that a net of 3.3 million people were
missed in the 2000 Census. "How can we accept 36 million errors and 8
million questionable cases as the most accurate census ever but refuse to
correct 3 million errors that scientific methods identify with confidence?"
asked Everett Ehrlich, Census Monitoring Board Member and former
Undersecretary of Commerce.
As defined by the Census Bureau, census error consists of three components
-- the numbers of omissions, erroneous inclusions and non-data defined
persons. Omissions are people who are missed in the census and erroneous
inclusions are people who were counted twice, counted in the wrong place,
or shouldn't have been counted at all, such as fictitious people, children
born after April 1st and people who died before April 1st. Non-data defined
people, sometimes referred to as "whole-person imputations," are
computer-generated estimates of the number or characteristics (such as age,
sex or race) of people in a household. There were 5.7 million of these in
the 2000 Census and 2.2 million in 1990. Uncertain cases include counts
where there is a high probability of error, or where there is so little
information that we can not tell if it is erroneous.
Re-instated possible duplications refer to the 2.3 million persons for whom
the Census Bureau could not definitively determine whether or not they
were counted twice.
Errors and Uncertain Cases in the Census, 1990 and 2000
||Erronious Inclusions (error)
||Non-Data Defined Persons (uncertain)
||Re-instated Possible Duplications (uncertain)
||Total Error and Uncertain Cases
The Census Bureau would not be able to say that Census 2000 is the "most
accurate census in history" without reviewing the results of the A.C.E.
Moreover, the A.C.E. tells us how many people were missed and how to adjust
the census accordingly. In an operation as large as the decennial census,
there are bound to be problems. The 2000 Census unfortunately includes a
massive number of errors. The following chart depicts the errors and
uncertain cases in the 2000 count.
"Should we accept the Census Bureau's relative definition of accuracy when
we know that the 2000 count contained as many errors as 1990," asked
Gilbert F. Casellas, Presidential Co-Chair of the Monitoring Board. "If
you're one of the millions of Americans not included in the final count,
the answer is no."
It is possible that the same person could be included in more than one
error or uncertain case category. However, despite possible offsetting of
errors, the vast numbers clearly indicate a massive census error rate.
Furthermore, the effects of errors in the census are differential by race
as evidenced in the chart below.
Errors and Uncertain Cases in the 2000 Census, by Race
||Non-Data Defined Persons
||Re-instated Possible Duplications
Dr. Eugene P. Ericksen, a decennial census expert and professor of
statistics at Temple University added, "The results from the 2000 Census
show us that the differential undercount was reduced, not eliminated, but
doesn't tell us how. It is very possible, for example, that the level of
omission in the 2000 Census was the same as or greater than the
corresponding 1990 level. The reduction in the differential undercount
could very well have been achieved by increasing numbers of erroneous
inclusions and non-data defined people. Moreover, there are additional
questions such as how did the so-called re-instated possible duplications
contribute to reducing the differential undercount? It is likely that these
re-instated possible duplications contributed to increased error in the raw
census count. For example, why is the racial differential undercount less
in the rural South than in the rest of the country? Does the fact that
many Blacks in the rural South were counted twice offset the missing of
others who were harder to count?"
"Now that we have information about census error, we still need to know
how many people were missed, how many people were counted twice, or how
many people were included by mistake. Until we have the answers to these
and other key questions, we can not determine the accuracy of Census 2000,"
added Casellas. In 1990, 8.4 million people were missed and 4.4 million
were counted twice, or incorrectly included for a net undercount of 4
The bipartisan Census Monitoring Board was established in 1997 to monitor
Census 2000 operations. Its findings are reported to Congress every six
months. For further information, visit www.cmbp.gov.