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Table 3 High cardinality of combinations of name and date of birth

From: An efficient record linkage scheme using graphical analysis for identifier error detection

Identifier Cardinality Average NHS numbers per identifier
National Health Service Number 1066339 1
Date of birth 35694 29.87
Surname, complete forename 829650 1.285
Surname, first letter of forename, date of birth 1065027 1.001316
Surname, first three letters of forename, date of birth 1066184 1.000234
Surname, complete forename, date of birth 1066519 1.000090
  1. For a set of complete identifiers from one data source (PAS), we show the cardinality (number of discrete values) for each of a series of possible identifiers, and average number of NHS numbers per identifier. This cardinality of NHS number and combinations of name and date of birth are similar.