Counting on your Co-operation

The confidential details you provide in next month’s census forms will prove valuable.


Listener: 2 March , 2013.


Keywords: Statistics;


On Tuesday, March 5, millions of New Zealanders will fill in census forms on behalf of themselves, their children and their dwellings. They will do so out of a civic duty, although given the importance of a comprehensive count of the state of the nation, they also have a statutory requirement to do so.


Later, Statistics New Zealand will release the number living in New Zealand and in each location on census night – especially important for drawing up the electorates that underpin our democracy. Then will follow a multitude of tabulations and cross-tabulations of our social characteristics and of the nation’s dwellings. The results will be anxiously scanned, because the delay from the Canterbury earthquakes means the errors of social projection after 2006 are greater than usual. I am regularly reminded what a nuisance the delay has been for my research work.


What happens to the data after that? The Public Records Act 2005 requires that the census forms be securely stored and retained for 100 years. Each is also converted into an electronic record that can be used only for statistical purposes – government agencies such as the police, immigration, Inland Revenue, Winz and the NZSIS may not access the individual records.


Their confidentiality is explicitly protected by the Statistics Act 1975 (as are all such unit records the department collects). Over the years, Government Statisticians (the chief executives of Statistics New Zealand) have said if the law were changed, they would resign rather than infringe the principle that in return for your civic co-operation, the information you provide is totally confidential. In many places in the world, the integrity of the official database is threatened by politicians. New Zealand’s is one of the safest.


Unit records can be released for legitimate statistical purposes. This is such a serious matter that the Government Statistician personally approves each release. (Researchers also sign an agreement that sets out the importance of confidentiality.)


Researchers are never interested in the individual record per se, but sometimes they may be trying to match one record with another. For example, the University of Otago Health Inequalities Research Programme (HIRP) at the Wellington School of Medicine matches census records against subsequent mortality records. The detail in the census unit record is invaluable in judging what may have influenced a death.


One issue is that people sometimes change their ethnic status when their circumstances alter. The ethnicity reported on their death certificate by the undertaker can be different from that ticked on census night. One cannot simply compare ethnicity at death with the national statistics of ethnicity.


Even so, people’s names and addresses are never disclosed. In any case, researchers do not have the time to look at individuals out of curiosity. Instead, they are happy to have the data without the personal details or, often in my case, aggregated up so they don’t even see a unit record. We are happy because too much detail clogs the computer (and the mind of the researcher). Moreover, the Government Statistician could withdraw access to the database, wrecking an entire research programme. (To see some of the valuable results from the HIRP, go to .)


What will happen in 100 years’ time when we are long dead? In the UK, 100-year-old census records are available to genealogists – descendants curious about their ancestors’ lives. I was able to use a household record from the 1901 English census to sort out a small confusion in one of my family lines. Sadly, our census records have not been kept from back then. Our descendants may be able to access ones as old as that in a century’s time, but they certainly can’t now.


A census enumeration is expensive and has to be run like a military campaign. It is more than justified by the uses we make of it. From this researcher, from all social researchers and perhaps from genealogists in 100 years’ time, thank you for your co-operation.