IPUMS-International high precision population census microdata samples: balancing the privacy-quality tradeoff by means of restricted access extracts

A breakthrough in the tradeoff between privacy and data quality has been achieved for restricted access to population census microdata samples. The IPUMS-International website, as of June 2006, offers integrated microdata for 47 censuses, totaling more than 140 million person records, with 13 countries represented. Over the next four years, the global collaboratory led by the Minnesota Population Center, with major funding by the United States National Science Foundation and the National Institutes of Health, will disseminate samples for more than 100 additional censuses. The statistical authorities of more than 50 countries have already entrusted microdata to the project under a uniform memorandum of understanding which permits researchers to obtain custom extracts without charge and to analyze the microdata using their own hardware and software. This paper describes the disclosure control methods used by the IPUMS initiative to protect privacy and to provide access to high precision census microdata samples.