Match String Filters

When a master index application matches incoming records against records that already exist in the master index database, you want to be sure the composite weights are not artificially inflated due to matching on default values in certain fields. One of the most common problems in matching arises from the SSN (or other national identifier) in person data. This field should be one of the most reliable identifiers of a person since the number is unique to each person and the field is typically required so it should not be null. This means that if the SSN of a person is unknown, the person entering the data must enter some value that is not a valid SSN. Often the numbers “999999999” or “000000000” are used. If an incoming record contains one of these values, the match process returns the full agreement weight for the SSN field against other records containing the default data. We know this match value is meaningless in this case.

You can reduce the number of inaccurate matches and potential matches by defining an exclusion list for specific fields in the match string. When a match filter is defined against a field and an incoming record contains an excluded value, that value is ignored in the match process and does not contribute to the composite match weight.