What to know
- Projects may be eligible to submit up to five free duplicate records for a person in the study.
- The National Death Index (NDI) may rerun the search of an original file up to three times for free in some circumstances.
- Learn more about when you can request free duplicate records or a free rerun on your data request from NDI.
Free duplicate records
If records have conflicting information, researchers may submit up to five free duplicate records for that person.
Researchers may request more than five duplicate records from the National Death Index (NDI). If approved, payment at the regular rate may be required for these additional duplicate records.
Examples of free duplicate records
- Only one record will incur a charge. The other three will be free of charge.
- NDI users must demonstrate that they have made a concerted effort to remove as many duplicate records as they could identify.
- Two duplicate records may be created using only one of those surnames. All other variables must be the same.
Prohibited use
Duplicate records should not be used to attempt to gather missing information about a study subject from NDI files.
For example, researchers cannot attempt to identify missing information about the subject's race through NDI by creating duplicate records to score a 'true match.' There is a risk of error if such demographic information is assumed to be the 'true' information for that subject.
NDI is required to provide information only about a person's date of death, state of death, death certificate number, and cause or causes of death. Contact NDI staff at 301-458-4444 if you need clarification for your unique situation.
Free reruns
NDI offers free reruns in two situations:
- If an error occurs in constructing the data files for submission to NDI.
- If researchers obtain additional information on study subjects that was unavailable at the time of the original submission.
NDI allows up to three free reruns of the original file that was submitted to NDI. Requests for more reruns after those three will be charged at the regular rate.
The rerun file should include all corrections, additions, and deletions. Researchers cannot add new subjects to the file or change the original range of years.
If the file contains more than one million records, requests will be subject to approval on a case-by-case basis.