The Net Undercount of Children in the Decennial Census Based on

Demographic Analysis

byDr. William P. O’Hare

O’Hare Data and Demographic Services, LLC

COPAFS Presentation, June 7, 2013

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Why Focus on The Undercount of Young Children in the Census?

• Young children have had high net undercount rates historically in the United States

• The net undercount rates of young Children have been increasing since 1980

• There is very little systematic scientific evidence about this problem

Presentation and Terminology

• “Undercount” versus “Difference”

• Net Undercount Here = Census - Estimates

• So negative number implies an undercount

• Positive number implies an overcount

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How Do We Know Who Is Missed In The Census?

• Demographic Analysis (DA) Compares census results to an independent estimate

based largely on birth and death certificate data

• Dual-Systems Estimates (DSE) Compares census results to a second follow-up survey conducted in selected areas (Called Census Coverage Measurement in 2010)

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2000 (age 0-9) 2010 (age 0-9) 2010 (age 0-4)-1.0

0.0

1.0

2.0

3.0

4.0

5.0

2.6

3.4

4.6

-0.5

0.20.700000000000001

Percent Difference Between Census Counts and DA and DSE Estimates for Young Children: 2000 and 2010

DA DSESource: O'Hare et al. 2012 SDA Presentation

Perc

ent D

iffer

ence

What is Demographic Analysis?

• Estimates for population under age 75 are based on historical components of change for cohorts: [births, deaths, net international migration]

P = B – D + NIM

• 99.6% of age 0-4 DA estimate is based on births

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Components of DA Estimates for Age 0-4

• Births = 21,076,000

• Deaths = 148,000

• Net International Migration = 244,000

Source: Census Bureau’s May 2012 DA Release

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Limitations of DA Estimates

• Only National Level Data

• Only Black and Non-Black Data Historically

• Only Net Undercount/Overcount Figures

• No Estimation of Uncertainty 8

Overall Results of 2010 Decennial

Census Look Good

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10

2010 Pop. Est

DA Middle Series

Census Count

CCM Pop. Census CCM Count

296

298

300

302

304

306

308

310

308.5 308.3 308.7

300.7 300.7

Comparison of Various 2010 Population Figures (in millions)

Good Overall Results Mask Important

Differentials

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Total Children Adults

-2

-1.5

-1

-0.5

0

0.5

1

0.1

-1.7

0.700000000000001

Percent Difference Between 2010 Census Counts and DA Estimates for Children (age 0-17) and Adults (age

18+)

Percent Difference

Source: Velkoff 2011, PAA Presentation

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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

-6.0-5.0-4.0-3.0-2.0-1.00.01.02.03.0

Percent Difference Between 2010 Census Counts and DA Estimates by Single Year of Age: 0-17

AGE

Percent Difference

Source: Census Bureau’s May 2012 DA Release

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

-10.0

-8.0

-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

8.0

Percent Difference Between 2010 Census Counts and DA Es-timates for Race and Hispanic Groups by Single Year of Age:

0-17

Hispanic

Black Alone

Black Alone or in Combination

Not Black Alone or in Combination and Not Hispanic

AGE

Percent Difference Note: Data on Hispanics is only available from the December 2010 DA Release.

The “Not Black Alone or in Combination and Not Hispanic” category is not a category used by the Census Bureau.The racial categories used here are the Modified Race Categories where people who marked “some other race” were assigned to one of the five major races categories,

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Difference Between 2010 Census and DA for People Under Age 5, by Sex, Race and Hispanic Origin

  Number PercentTOTAL 972,000 -4.6FEMALE 471,000 -4.5MALE 501,000 -4.6BLACK ALONE OR IN COMBINATION 247,000 -6.3

HISPANIC 414,000 -7.5NOT BLACK ALONE OR IN COMBINATION AND NOT HISPANIC

309,000 -2.6

Note: Data on Hispanics is only available from the December 2012 DA Release.The “Not Black Alone or in Combination and Not Hispanic” category is not a category used by the Census Bureau.The racial categories used here are the Modified Race Categories where people who marked “some other race” in the Census are assigned to one of the major race categories.

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How Does the Data form 2010 Compare to Earlier

Censuses?

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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

-4.5

-4.0

-3.5

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

Mean Percent Difference Between Census Counts and DA Estimates by Single Year of Age from 1950 to 2010

Age

Percent Difference

Source; Census Bureau's May 2012 DA Release and Internal Census Bureau Historic file

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1950 1960 1970 1980 1990 2000 2010

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

1.0

Percent Difference Between Census Counts and DA Estimates for Adults and Young

Children: 1950 to 2010

Ages 0-4

Adults age 18+

Percent Difference

Source: Census Bureau’s May 2012 DA Release and internal Census Bureau Historic File

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Key Findings• Children have a net undercount & adults have a net overcount in 2010 Census

• Net undercount rates of children vary by age and race/ethnicity

• Younger children (under age 5) have the highest net undercount rate (4.6%) in 2010 and there is a net overcount for persons age 14 to 17

• Black and Hispanic children account of most of high net undercount of young children and net overcount of 14-to-17-year-olds.

• High net undercount of young children is not new…..The age structure of net undercounts for children is relatively consistent since 1950

• 1950 to 1980, net undercount rates for adults and young children fell, but 1980 to 2010, net undercount of adults fell while undercount of young children increased

KEY QUESTIONS1. Why are there such high net undercount rates for young

children in the census?

2. Why is there a net overcount rate for 14-17 year-olds in the 2010 Census?

3. What accounts for the strong correlation between net undercount rates and age among children?

4. Why has the net undercount rate for young children increased since 1980?

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Some Potential Reasons for High Net Undercount of Young Children

1. DA Estimates for young children are too high

2. Problems in collection and processing of data in Census

3. Time constraints among parents of young children

4. Young children live in households and families that are difficult to enumerate

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Hypothesis - DA Estimates for young children are too

high

Emigration of young children

• Pitkin and Parks (2005) hypothesize many children born to foreign-born (Mexican) women move to Mexico at a young age and are not picked up in DA emigration statistics.

• But, 0-4 year-olds missing in 2000 were found as 10-14 year-olds in 2010.

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Hypothesis - Systematic errors in census-taking or

processing lead to net undercount of young

children

The Census Questionnaire

• Continuation Form …Persons 7-12 need follow up (NRFU Persons 6-12)

• Young children are likely to be listed last on Census Questionnaire

• 10% of young children live in 7+ person households compare to 3% of adults

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Several Improvements in the 2010 Census Form

• Added age to information collection on persons 6-12 on primary questionnaire

• Added a new “administrative” question about people who were left off roster

• Added instruction about “including babies”• Added instruction about “child custody”• Partnership with American Academy of

Family Physicians and Planned Parenthood

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Despite improvements, net undercount of young children increased between 2000 and

2010

Age Imputation

Hypothesis - Too many people who should have had age imputed as 0-4 got age imputed as 14-17 (or other age groups)

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29

0 1 2 3 4 5 6 7 8 9 10111213141516170.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Age Allocation Rates

2000 Census 2010 ACS

AGE

Percent Allocated

Source: Analysis of PUMs files on IPUMS site

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Hypothesis - Parents of young children don’t complete the census questionnaire because of time demands

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2000 Census Mail-Back Rates by Presence of Children and Family Type

 Census Mail-Back Rate

Live Alone 86%Single with adult roommates 73%Single with kid(s) 63%   Married with no kids 90%Married with kid(s) 83%Source: Hillygus, Nie, Prewitt & Pals, 2006, Table 4.4

Hypothesis - Young children live in the kinds of households and living arrangements that are difficult to enumerate

Living Arrangements of Young Children

• 10 characteristics of Hard-to-Count populations identified by Census Bureau in Planning Data Base

• Young (age 0-4) Black and Hispanic children higher on every one of the 10

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In Building with 2+ units

In Poverty In Rental unit Moved Last Year

0

10

20

30

40

50

60

70

80

21

16

31

15

4346

70

3735 36

60

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Percent of Adults, Black Children Age 0-4 and His-panic Children Age 0-4 with Selected Hard-to-Count

Characteristics

Adults

Black age 0-4

Hispanic age 0-4

Percent

Source: Analysis of 2010 ACS PUMS file on IPUMS system

Summary• Young Children have higher net undercount rate than

any other age group in 2010• Young children have had relatively high net

undercount rates since 1950• The trends in net undercount rates of young children

and adults have diverged since 1980• Need to develop understanding of WHY young

children have high net undercount rates in the census

• One focus of 2020 Census planning should be households with young black or Hispanic children

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THANKS

Contact Information

William O’HareBillohare1@gmail.com