But he said the study still fell short of an inquiry by Australian unions last year which found 40 per cent of Australian workers were in insecure work.
"The NZ data takes no account of 'dependent' contractors (employees of an employer skirting the law by defining its workers as 'independent contractors'), who are included in the Australian count," he said.
The headline figure - that "at least 30 per cent of our workforce are insecure" - is based on an unusual measure of the workforce that includes the unemployed but excludes employers.
Temporary employees increased from 7.7 per cent of the workforce in 2008 to 8.6 per cent last December, the unemployed jumped from 4.5 per cent to 7.2 per cent, and "permanent" employees who said they had a medium to high chance of losing their jobs in the next year rose from 9.3 per cent to 12.6 per cent.
The total of "workers most at risk" increased from 21.5 per cent of the non-employer workforce to 28.4 per cent.
Self-employed people shrank from 11.6 per cent to 9.4 per cent, as many small one-person businesses apparently succumbed to the recession.
Statistics NZ does not measure how many of the surviving self-employed still feel at risk of going out of business, but the union study argues that if they were included the total of all insecure workers would be "at least 30 per cent".
"Underlying all this is a 'just-in-time' approach to staff hiring [and firing]," it says.
"Virtually every major contract in fast-food has no minimum or guaranteed hours," said Unite Union director Mike Treen, adding: "Security contracts have no minimum."
Statistics NZ found that temporary workers increased from 9.2 per cent of all women in paid work in 2008 to 10.8 per cent last December, while for men the increase was only from 6.3 per cent to 6.8 per cent.
The highest rate of temporary work was in education, rising from 14.2 per cent of the workforce in 2008 to 16.7 per cent.
Fluctuating fortunes
Death of a client is not just emotionally draining for home care worker Ngapera Rangiaho - it also costs her money.
Mrs Rangiaho, 48, works an average of 20 hours a week caring for five clients in their homes. But her income fluctuates hugely depending on whether those clients come into or leave the business she works for, go into respite care, or die.
"A few weeks ago I was drawing in maybe $1200 a fortnight, till there was a release of a client and now I am on $500 or $600 a fortnight," she says.
"We get the email to say our services are no longer required ... When they pass away, how we are notified is, 'Please do not return to the home, the client has passed away.' And that's the end of it."
She travels 40km into Hamilton each day, leaving her home at Orini at 6.15am so she can get to her first clients, two teenage brothers, in time to get them ready for school.
"Then I move on to another client who has had a stroke. So everything varies," she says.
She and her husband, who has "a set salary", are paying off a mortgage, so when her hours drop suddenly Mrs Rangiaho takes hours out of her paid annual leave to maintain the household income. Yet she is committed to her work despite a low pay rate of just over $14 an hour.
"I'm just fortunate that I have an understanding husband."
