What’s in a Name? Accounting for Naming Conventions in NCHS Data Linkages
Eric A. MillerNational Center for Health Statistics (NCHS)
2012 FCSM Statistical Policy SeminarDecember 4, 2012
“Two men say they’re Jesus. One of them must be wrong.”
Mark Knopfler, Dire Straits
• One reason for data sharing is data linkage
• Assessing the quality of linked data is different from assessing a standalone dataset• The quality of variables from a specific source doesn’t
matter if the linkage is poor• Problems with linkage can produce poor quality data
– Are the data fit for use? + Are the data fit for linkage?
What Does This Have to do With Data Quality?
Names• Names are commonly used in data
linkages• Important to account for name differences
and naming conventions to produce a high quality linked data file
Quick Background on Data Linkage
• Deterministic– Exact match on linkage
variables• Frank ≠ Francis
• Probabilistic– Accounts for imperfect data– Probability of a match
• Frank ≈ Francis
Caveats of Data Linkage• It’s not perfect
Prince ?Prince Rogers Nelson
Prince
Some things are out of our control!
Caveats of Data Linkage• Varying levels of quality for linkage
variables can substantially increase workload – Clean-up, reformatting– Clerical review
• Analysis of insufficiently linked data can produce biased estimates
Example - Hispanic Paradox• Despite having a higher risk profile,
Hispanics have been found to have lower mortality rates compared to non-Hispanic whites
Markides and Coreil (1986). Public Health Reports; 101: 253-265
Mortality Rate per 100,000 Among Women in 1986-1990 National Health Interview Survey Linked to 1991 National Death Index
Age 18-44 Age 45-64 Age 65+0
1000
2000
3000
4000
80
642
3504
182
969
3928
97
480
2438
White-NH Black-NH Hispanic
Rat
e pe
r 100
,000
Liao et al. (1998). Mortality Patterns among Adult Hispanics: Findings from the NHIS, 1986 to 1990. AJPH.
Potential Reasons for Paradox• Health selective immigration• Salmon bias (return migration)• Advantageous health behaviors and social
support• Data quality / Insufficient linkage
Potential Reasons for Paradox• Data quality / Insufficient linkage
– Naming conventions for Hispanics differ from other US populations
• Use of mother’s and father’s surname• May not have single middle name
– Less likely to have social security number• Especially among older adults and foreign born
Percent of “True” Matches for Hispanics and Non-Hispanic Whites by Foreign-Born Status
Hispanic Non-Hispanic White
Foreign-born US-born Foreign-born US-born
Class 1 (“True”)Matches
32.5% 50.0% 57.4% 62.5%
Class 1: records agree on at least 8 digits of SSN as well as first and last name, middle initial, and birth year (+/- 3 years)
Joseph Lariscy. Differential record linkage by Hispanic ethnicity and age in linked mortality studies: Implications for the epidemiologic paradox. J of Aging and Health (2011); 23: 1263-1284.
What does this have to do with NCHS?
• NCHS Record Linkage Program– Links survey data with data collected from
administrative records– Designed to maximize the scientific value of the
NCHS population-based surveys– Examine factors that influence chronic disease,
disability, health care utilization, morbidity, and mortality
14
Linked NCHS surveys• National Health Interview Survey (NHIS)
• 1999-2004 NHANES, NHANES III, and NHANES II
• NHANES I Epidemiologic Follow-up Study (NHEFS)
• The Second Longitudinal Study of Aging (LSOA II)
• National Nursing Home Survey (NNHS)
15
• National Death Index
• Medicare and Medicaid enrollment and claims
• Social Security Administration Retirement and Disability
• Pilot projects– Florida Cancer Data System– Texas Supplemental Nutrition Assistance Program (SNAP)
Linked Administrative Records
Case Study: NCHS Survey linkage with the NDI
• National Death Index (NDI)– A national file of identifying death record
information (beginning with 1979 deaths)– Every four years we send a file of survey
participants to NDI to conduct a linkage and identify participant deaths
– We take additional steps to try and improve the linkage
NDI Matching Algorithm• Social Security Number• First name• Middle initial• Last name• Month of birth• Year of birth• Sex• Father’s surname• State of birth• Race• State of residence• State of birth• Marital Status
Unweighted percent of NHIS sample adults aged 18 or older, refusing to provide SSN, 1997-2009
NCHS Record Linkage Program
• To make sure we provide research quality data, we spend a lot of time processing the data to increase the chance of finding a true match– Try to increase the number of matches while
minimizing false matches
• Addressing name clean-up and naming conventions is a major activity
Methods – Name Clean-up • Fix invalid characters• Compress spaces• Remove titles/descriptors/suffixes
– e.g. Mr., baby, jr.
• Linkage uses NYSIIS phonetic codes– Accounts for misspellings or unusual spellings
Methods – Name Clean-up • Create alternate records
– Sent with original record• Among women substitute surnames for last name• Nicknames (using a look-up table)
– Substituting Elizabeth for Beth
Nickname Lookup TableSEX NICKNAME PROPER NAMEM ABE ABRAHAM
F AGGIE AGNES
M AL ALBERT
M ALEX ALEXANDER
M ALF ALFRED
F ALLIE ALBERTA
M ANDY ANDREW
Example: If first name=‘Andy’ then alternate record first name=‘Andrew’
Methods – Name Clean-up – Accounting for Hispanic and Asian naming
conventions• Hispanic
– Hispanic nickname lookup table– switch middle and last
• Asian– switch first and last
Hispanic Lookup TableSex Formal Name Nicknames
F Adelina Deli Lina
F Adelaida Ade Adela
M Adrián Adri
F Adriana Adri
M Alberto Alber Albertito Beto Berto Tico Tuco Tito
M Alejandro Ale Álex Alejo Jandro Jano Sandro
F Alejandra Sandra Ale Álex Aleja Jandra Jana
M Alfonso Alfon Fon Fonso Fonsi Poncho
F Alicia Ali Licha
Alternate Records Example
Number First Middle Last
1 David Américo Arias Ortiz
2 David Américo Ortiz
3 David Américo Arias
4 David Américo
5 Big Papi
Conclusions• Care needs to be taken to avoid false links
– Alternate records increases the number of potential matches
• If two men claim they’re Jesus, they can both be wrong
– Need a higher level of scrutiny to determine that a pair of records match
Conclusions• Accounting for name differences and naming
conventions improves quality of the linked-data product
• Hope our efforts to account for Hispanic and Asian naming conventions reduces potential bias – Need to evaluate
Important Considerations• How are names are collected?• How are the names recorded? • More likely to have formal names versus
nicknames?– Surveys may differ from official documents
• Are maiden names (surnames) available?• Are there consistent rules for recording
names?
Acknowledgements• Dr. Jennifer Parker• Dr. Dean Judson
Thank you
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