On census boycotts Professor Fiona Stanley Distinguished Research Professor, University of Western Australia; Professor Terry Nolan, Melbourne School of Population and Global Health and Professor John Mathews, Melbourne School of Population and Global Health write: Re. "What you risk when you boycott the census" (yesterday). Most Australians would expect that personal information, collected at public expense, would be routinely aggregated, de-identified to protect privacy, and used to the fullest extent possible for public benefit purposes. However, there have been recent media comments and concerns that the use of census records by the Australian Bureau of Statistics (ABS) constitutes a breach of privacy and a breach of trust in “tracking” individuals. On the contrary, privacy has not been breached, as the Australian Statistician has a legal obligation to collect information for public benefit purposes, and he has been scrupulous in protecting the names and identifying details of all individuals. ABS has simply linked census records to other records collected at public expense to create an aggregated but de-identified data set that will be even more valuable for the planning of services and other public benefit purposes. Other ground-breaking work in Australia has already used aggregated but de-identified data to document important risks that would otherwise have gone unnoticed or been imperfectly understood. These include risks from folic acid deficiency in pregnancy, risks of blood clots from long-haul air travel, and the increased cancer risks after CT scans (medical x-rays) in childhood. In our increasingly complex world, members of the public should be reassured that, without risk to privacy, the personal information collected from them can be aggregated and used in such ways to inform and protect them, and to increase the efficiency and effectiveness of public services. Indeed by understanding, approving and monitoring the use of de-identified information in this way, citizens are extending the social compact that that they have made with each other and with government for their mutual benefit. The Productivity Commission is currently exploring issues around the availability and use of data in Australia. The Commission will realise that the use of Australian data for public benefit purposes is lagging behind what is possible in UK, Canada, New Zealand and other democracies. Australian developments have been inhibited by concerns about whether it is possible to guarantee privacy protection. However, the experiences in Australia and overseas show that data aggregation projects have not led to breaches of privacy, and that any theoretical risks are more than justified by the countervailing public benefits. Thus with support from the public, and with stringent legal penalties for any attempt to breach privacy, Australia will be poised to make major advances in its use of data for public benefit purposes. We congratulate the Australian Statistician for his leadership in this important area of public policy and practice.