Table 4.

Qualitative summary of causes for discordance between identifier field pairs within linked records.

Identifier Field	Qualitative Assessment
Birth Weight (Exact)	Birth weights disagreed by one or two grams Miskeyed, missing, or transposed digits in one record
Date of Birth	“Day” component of date disagreed by one or two days Transposed digits within the “Day” component
Infant First Name	Transposed first and surnames in one record Inconsistent name spelling Use of an alias in one record
Infant Surname	Inconsistent name spelling Use of hyphenated parental surname in only one record Matches maternal surname in one record and paternal in the other
Infant Sex	Incorrectly coded value in one record, in several cases a child with a first name like “Infant Boy” was assigned “Female” sex within the same record.
Mother First Name	Inconsistent name spelling Use of an alias in one record
Mother Surname	Inconsistent name spelling Use of father’s rather than mother’s surname in one record
Street Address	Completely different addresses listed Inconsistent spelling of street names Inconsistent street suffixes (e.g. “Boulevard” versus “Blvd.” or “Street” versus “Drive”) Inconsistent formatting of apartment abbreviations (e.g. “Apt 3” versus “#3”) Miskeyed or transposed digits in street number of one record
Zip Code	Miskeyed or transposed digits in one record Erroneous zip code in one record (street addresses match, one zip code is incorrect)