However, because the target took into account students who were learning outside of school - at tertiary institutions or gaining trade qualifications - a new figure was not yet available.
"What we are trying to do is get a simpler way of telling what is quite a complicated story ... we do know that the 18-year-old target will be going up, because we know that the 16-year-old rate of achievement is going up."
Ms Parata said last week's Budget, in which $19 million was set aside for the first partnership schools, would help raise the results of the most disadvantaged students. Teacher union criticism that initiatives such as partnership schools were at the expense of public school funding was unfounded, she said.
"No parent will be compelled to send their kid to a partnership school.
"But those kids are part of the New Zealand public, whatever school they're at.
"They are to be funded, whatever choice their parents make.
"So I don't understand the analysis that says that these kids who deserve education are somehow stealing it from the public system. They are part of the New Zealand public."
It was "absolutely our expectation" that partnership schools will be efficient and achieve results, and they would be held to a public contract.
"They will have a clear contract clause that says they will be shut down if they don't meet them, and they can and will be shut if they don't.
"Now that is a significantly higher bar than we impose across the rest of our system," she said.
President of the Post Primary Teachers Association Angela Roberts said if the Government wanted to raise NCEA pass rates it made sense to put money in to public secondary education, which she said was a "loser" in the Budget.
"It's a lot of money to be investing in two or three [partnership] schools - $19 million would buy you a lot of reading recovery ... why not put it into something that is absolutely proven to help kids?"
Secondary Principals Council head Allan Vester said Ms Parata's focus on lifting achievement was commendable, however "within the sector there are serious concerns about the [85 per cent] target".
It could incentivise behaviour which was not in a student's best interest, he said, including a focus on picking up credits, no matter their quality or overall usefulness.
"It could mean that students ended up with a mix of credits that lack coherence in terms of the next step in education, training or employment."
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