Until very recently the Bureau of Statistics had next to no idea how long Indigenous Australians lived.
It relied on the data funeral directors produced when they ticked boxes on death certificates. Crudely adjusted for guesses about under-reporting, it showed Indigenous Australians dying an average of 17 years earlier than the rest of the population, the figure quoted by former prime minister Kevin Rudd in his apology to Indigenous Australians in 2008.
But behind the scenes the figure was mocked. It seemed to show Australia performing far worse than other nations with Indigenous populations. So during the 11-month window in which it retained the names on the 2006 census forms, the Bureau tried something better. It linked the names to the names on death certificates.
What it found was shocking, in a good way. Instead of dying 17 years earlier, Indigenous Australians were dying 10 years (women) to 12 years (men) earlier.
Sydney University demographer Richard Madden says his initial reaction was "fear".
"I thought that politicians would say: 'Oh we've got the gap down from 17 years to 10, we don't need to do as much'. Amazingly, that didn't happen. Apart from that, my reaction was delight that we now had a much, much better, more rigorous method of looking at life expectancy."
The rigor was improved in 2011 census in which names were once again linked to death records for a limited time and will be improved further in next week's 2016 census when for the first time names will be kept and linked to other data for four years, enabling a more detailed breakdown of Indigenous deaths by age and gender.
University of NSW demographer Ching Choi says the longer names are kept the better.
"The longer you link deaths, the more deaths you record. The number of Indigenous deaths each year is very small, around 2000 to 3000. If you want to analyse, say, Victoria, you are talking about only a few hundred. So if you keep names for more months you get better quality data."
The Bureau's plans to hang on to the names we provide on Tuesday week has aroused the ire of privacy experts and a former Australian Statistician, Bill McLennan, who says it's "without doubt the most significant invasion of privacy ever perpetrated on Australians by the ABS".
But Australian National University demographer Liz Allen sees it as way to make surveys less invasive.
"If you were to ask people what medication they are taking, most probably wouldn't be able to tell you or would find the topic too sensitive," she says. "But linking the census data to pharmaceutical benefits records can get that data and get it linked to all sorts of other information without the need to go back to people over and over again."
Labor frontbencher Andrew Leigh said the Turnbull government had "botched" explaining the change but urged Australians to complete their forms accurately regardless.
"Extraordinarily, there seems to be some confusion in the government about which minister is responsible for the census," he said. "Treasurer Scott Morrison and Financial Services Minister Kelly O'Dwyer have left the task of explaining this solely to the Australian Bureau of Statistics, which is already busy enough without having to do their jobs as well."
Fairfax Media understands that late last week Small Business Minister Michael McCormack was given responsibility for the ABS, a role previously held by the parliamentary secretary to the treasurer, Alex Hawke, whose post was abolished in the post-election reshuffle.
Dr Allen said the census names would be coded and closely guarded. Under the Census and Statistics Act not even the Prime Minister could demand access.
In The Age and Sydney Morning Herald