The term record linkage was first used by the chief of the U.S. National Office of Vital Itt% Statistics, Dr. Halbert L. Dunn in a talk given in Canada in 1946. Dr. Dunn advocated the use of a unique number (e.g. birth registration number). Each person in the word creates a book of life. The book starts with birth and ends with death. Its pages are made up of the principle events of life. Record linkage is the name given to the process of assembling the pages of the book into a volume. Historically record linkage was assigned to clerks who would search and review lists to bring together the appropriate pairs of records for comparison, seek additional information when there were questionable matches, and finally make decisions regarding the linkages based on established rules.