National Leader Don Brash used a wildly inflated number when he told the Ratana gathering on Monday that nearly half of all Maori children were dependent on a benefit.
The figure - which strongly featured in news reports of the high-profile Maori gathering - was the result of a calculating error by the Parliamentary Library.
The estimate should have been 30 per cent, said parliamentary researcher David Williams, who owned up to the Herald about making the mistake. He has apologised to Dr Brash.
Dr Brash revealed he was "absolutely livid" when he found out about the error just hours before he was due to once again highlight the disturbing statistic in his Orewa speech.
"I heard about it at about a quarter to five yesterday [Tuesday] afternoon as I was walking in to the TV studio to do a pre-record with Susan Wood," he told the Herald.
"My initial reaction was 'it cannot be right', I've had all these figures checked and double-checked. I pointed out I used it the day before at Ratana. And the message came through from Parliamentary Library 'terribly sorry we gave you the wrong figure'.
"We managed to get all the text changed in the stuff that went out to the media [for Orewa] and sent out a correction immediately.
I am going to write to Ratana and regret the error."
Mr Williams believed the error occurred when he transferred working figures from an Excel spreadsheet.
Herald inquiries indicate it is very difficult to pinpoint exactly just how many Maori children are dependent on welfare, given mixed-race parentage.
Using Statistics New Zealand and Ministry of Social Development figures, Mr Williams derived the 30 per cent by taking the number of all children dependent on a benefit at July 2, 2004 (246,595) and estimating that 65,700 of them were Maori under 15. He then divided the estimated total number of 216,000 Maori under 15 by 65,700 to come up with the 30 per cent figure.
Dr Brash said he had used the 50 per cent number atRatana "quite strongly - it was a hell of a figure".
"I had a prepared text and I had that figure for the Orewa speech - and thought what better place to use it - so I plugged it."
The mistake was unearthed when a National aide asked the library to recheck all the figures before Dr Brash gave his pivotal Orewa speech.
Monday: Nearly one half of all Maori children are dependent on a benefit - speech at Ratana celebrations
Tuesday: Nearly one-third of all Maori children are on a benefit - corrected Orewa speechBy Fran O'Sullivan Email Fran