Software can perform various comparison routines to determine whether a person applying for registration is already registered, perhaps for another address. Electronic searches can be programmed into voter registration databases to identify whether a person applying for registration is already on the register. As people do not always use the exact same name every time they complete a form, software comparison routines need to make use of 'fuzzy matching' techniques to help identify possible duplicates. Using fields other than names can also assist, particularly date of birth records. Even with dates of birth, people can show different dates on forms over time, and 'fuzzy matching' may also be needed when comparing dates of birth.
'Fuzzy matching' involves programming a computer system to search for matching data by applying various criteria. For example, a possible match could be identified where a name was the same except that one letter might be different. Possible matches could also be identified where first names and surnames matched, but middle names did not match or were absent in one record but not another.
Names can also be matched using 'aliases'. A system can be set up that compares different variations on the same name, which could be used by a person at different times. For example, aliases for John could include Jon, Jonathon or Johnstone; aliases for Catherine could include Katherine, Caterine, Katerine, Kate, Cate, Caitlyn, and so on.
Matching techniques also need to take account of people changing names. In some societies, a woman typically changes her surname when she marries. People also change their names by deed poll. Where this occurs, matching by surname will generally not find a match with an earlier record using the old name. In these cases matches can be found using first name or given name fields and dates of birth. To assist with this process, it is desirable to ask voters on their registration forms whether they have changed their names since their last registration, and to ask for their previous registered address. This data, if supplied, can greatly assist in finding out of date entries.
Fuzzy matching programs often produce several possible matches with a current record, some or all of which may not be actual matches with the person concerned. A human operator should be used at this point to determine whether any possible matches are actual matches, and alter the relevant records as necessary.
