Linking the 1980 PostEnumeration Program Samples 

to the Decennial Census

Kelsey J. Drotning and Katie R. Genadek

2023 FCSM Conference

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Any conclusions expressed herein are those of the authors and do not reflect the views of the U.S. Census 

Bureau. All results were approved for release by the Disclose Review Board of the U.S. Census Bureau 

(Data Management System number: P- 7522572, Disclosure Review Board (DRB) approval 

number: CBDRB-FY23-ADEP001-006.
How the Census Bureau Links Records

All cases linked to a common “composite file” of administrative 

records

• Most common linkage keys: name, date of birth, sex, place of 

residence

• Uses standard techniques of data cleaning and probabilistic 

matching

• Matched cases are assigned a Protected Identification Key 

(PIK)

• Data assigned PIKs can be linked to any other data with PIKs

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1850-1930 

Censuses

1940 

Census

1950-1990 

Censuses

2001-2022 

ACS

User-provided Data

Examples: clinical trials, 

administrative records, surveys

Administrative Records

Examples: SSA Numident

Data Linkage Infrastructure

Census Surveys and Data

Current Population Survey (1973, 1978-present)

American Housing Survey (1983-present)

Survey of Income and Program Participation (1984-present)

Longitudinal Employer-Household Dynamics (LEHD) Data

 

2000-2020 

Censuses
Existing linked Decennial Census of Populations

1940 1950 1960 1970 1980 1990 2000 2010 2020

2000-2020 

Census 

2001-

American 

Community 

Survey

1940 

Census
•Microdata files for 1960-1990 exist but do not include names

•Names were handwritten on census forms

•Census forms are stored on 250,000 microfilm reels

•Forms and data are highly restricted to protect respondent 

confidentiality

Why is this difficult?

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The Decennial Census Digitization and Linkage 

(DCDL) Project

• Initiative to produce linked microdata files from the 1960 –

1990 Censuses

• 1950 Census is currently being digitized and will be linked 

into infrastructure 

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Project Phases

1. Digitization: Scanning the microfilm

2. Capture: Recovering handwritten respondent names from 

scans

3. Merge: Attaching names to otherwise complete microdata 

files

4. Linkage: Assigning Protected Identification Keys (PIKs) to 

the data

5. Dissemination: making linked data available to researchers 

in a restricted environment

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Digitization: Microfilm Scanning Ongoing

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Digitization: Project Status

• Follow our progress on the DCDL website: www.census.gov/dcdl

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Capture: Optical Character Recognition (OCR) 

and Optical Mark Recognition (OMR)

• Partnering with a team from Information Sciences Institute 

at University of Southern California

• Performed best on 1990 Census Pilot in 2015

• 2020 Census Bureau Data Capture team working on custom 

OMR

• Production OCR and OMR to begin in 2024

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Linkage: PIK Assignment

• Assign PIKs by adapting standard Census Bureau linkage 

methods

• Make use for 1969-1989 IRS 1040 full universe files

• Harmonized addresses in IRS data to Census geography

• Recovering 1970, 1980 Census address lists

• Adapt linkage strategies on samples of census data with 

names 

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The 1980 Enumeration 

Sample (E-Sample)

• Original Purpose: To estimate 

erroneous enumeration in the census

• Sample: 110,000 housing units from 

1980 Census 

• Method: Enumerator interviews

• Capture: Keyed in Name respondents

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1980 Census Sample for Linkage

• Link the E-Sample to 1980 Census data

• Attach Names from E-Sample to 1980 Census record

• Use the 1980 Census records with names for development of 

PIK assignment strategies 

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Record Linkage

• Linking based on household and personal characteristics

• Variables: geography, sex, race, age, marital status, relationship to 

household head

• Deterministic record linkage: Exact matching

• Probabilistic record linkage: Window blocking on age (+/- 1)

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Results - Region

15

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

Northeast Midwest South West U.S.

Percent Matched

Census Region

Percent of E-Sample Records Matched to the 1980 Census by Region

Deterministic Probabilistic

All results were approved for release by the Disclose Review Board of the U.S. Census Bureau (Data 

Management System number: P- 7522572, Disclosure Review Board (DRB) approval number: CBDRBFY23-ADEP001-006.
Results - Sex

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0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

Deterministic Probabilistic

Percent Matched

Sex

Percent of E-Sample Records Matched to the 1980 Census by Sex 

Male Female Source: 1980 E-Sample, 1980 Census

All results were approved for release by the Disclose Review Board of the U.S. Census Bureau (Data Management System number: P- 7522572, Disclosure Review 

Board (DRB) approval number: CBDRB-FY23-ADEP001-006.
Results - Race

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0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

White Black Japanese Chinese Filipino Asian Vietnamese American

Indian

Pacific

Islander

Other

Percent Matched

Race

Percent of E-Sample Records Matched to the 1980 Census by Race

Deterministic Probabilistic Source: 1980 E-Sample, 1980 Census

All results were approved for release by the Disclose Review Board of the U.S. Census Bureau (Data 

Management System number: P- 7522572, Disclosure Review Board (DRB) approval number: CBDRBFY23-ADEP001-006.
Conclusions

• Linked 38% of E-Sample to 1980 Census data

• Record linkage using historical data is challenging due to the lack of 

unique identifying variables

• Probabilistic record linkage performs slightly better than deterministic 

record linkage, but there are still a lot of records we are unable to link

• 1980 Census sample with names ready for PIK assignment

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DCDL 

Team

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