A breakthrough in the tradeoff between privacy and data quality has been achieved for restricted access to anonymized population census microdata samples of Europe. As of September 2007, the IECM website, in partnership with the Minnesota Population Center, offers integrated microdata for 22 censuses, totaling more than 31,2 million person records, with 7 European countries represented. Over the next two years, the European collaboratory led by the Centre d’Estudis Demogràfics and the Minnesota Population Center, with major funding by the 6th Framework, United States National Science Foundation and the National Institutes of Health, will disseminate samples for more than 25 additional censuses. Thanks to high precision samples of one, five and even ten percent, much research on the ageing of populations can be accomplished. Nevertheless for studies of the oldest-old, over-samples of the elderly will often be required. The paper examines basic statistics on headship rates in the samples currently available and illustrates some of the limitations that can best overcome by oversamples for elderly populations.