New Zealanders have little idea how their personal information - including on household income and ethnicity - is collected and sold, a government watchdog warns.
The Privacy Commissioner wants powers to monitor companies that collect and sell personal information.
"Data brokers" collect publicly available information and personal details gathered by other means, including surveys doubling as prize giveaways.
They may know details about you or your household, including ethnicity, property value, what foods you buy and how often you travel.
One of the world's largest data brokers, Acxiom, has a New Zealand operation in nondescript offices on Karangahape Rd in central Auckland.
Another information source is your postie - NZ Post's Genius segmentation tool enables household profiling by income and ethnicity.
Assistant Privacy Commissioner Blair Stewart said the Privacy Act was now enforced by way of complaint.
His office has backed a Law Commission recommendation that the law be changed so the Privacy Commissioner can serve compliance notices on companies.
"People don't tend to complain about certain practices, if the sort of practices go on in the background and they can't see what's happening."
That view was supported by Auckland University Business School's Gehan Gunasekara, a specialist in information privacy law, who said the law did not cover such practices.
It did not recognise, for example, that privacy could apply to groups, or that some information was more personal than other information.
"New Zealanders are giving away far too much information about themselves, not really knowing what it's going to be used for," he said.
Several companies in New Zealand sell access to information on individuals or, more commonly, households.
NZ Post's Genius tool divides New Zealand addresses into clusters and segments described by more than 1000 data variables.
A sample map on NZ Post's website shows the Auckland suburb of Sandringham in the bright yellow of "Rice and Shine" homes, while Mt Roskill has more "Pacific Blend" light blue.
The Rice and Shine group has a "strong skew towards Asian ethnicity" and spends "above average on cars and smash repairs".
Genius is built from a variety of data sources, including NZ Post's own national surveys.
Another operator is Mosaic NZ, which uses data from the census, QV, Land Information New Zealand and surveys done by market research company Roy Morgan.
Most mid- to large-size companies, as well as charities such as the Fred Hollows Foundation, use data brokers.
Privacy Commissioner Marie Shroff raised concerns about NZ Post's first national survey, in 2009, saying people were confused about whether it was compulsory.
Nigel Paxton, head of the NZ Post division that includes Genius and direct marketing, said organisations had the legal right to target certain people.
"The key thing for any commercial organisation is that if it's operating within the law, then please don't confront them with moral issues," Mr Paxton said.
The Government is expected to respond to the Law Commission's recommendations next month. - The New Zealand Herald