To double down means to engage in risky behaviour, especially when one is already in a dangerous situation. This is the year of the NCEA's statutory review; New Zealand sits at a perilous crossroads.

Will we respond to the evidence of plummeting educational standards and increasing inequity? Or will we double down, blinded by the idealism that has always underpinned the National Certificate of Educational Achievement?

Born out of discontent with the old university-dominated system, NCEA has ambitious and noble aims. More revolution than evolution, it was designed to accredit meaningful learning gains of all students. And depending on how you measure progress, some believe it has succeeded.

This year, 90 per cent of school leavers achieved Level 1 and 54 per cent achieved Level 3, up from just 30 per cent when NCEA began in 2002-2004. By anyone's reckoning this is a pleasing trajectory.

Even more pleasing is that the achievement gap between decile 1 and 10 schools has narrowed, from 53 to 44 percentage points at Level 3. So what exactly is there to dislike about our national qualification? Chiefly, it's about expectations.

In most developed countries all students are assessed on a core curriculum, a safety net, of essential subjects at age 15 or 16. By communicating meaningful minimum expectations, this drives up standards, especially for disadvantaged children.

But in New Zealand, in the name of flexibility, we've stripped away the safety net almost completely. It is as if a national certificate (regardless of whether you can read, write or add up) can somehow magic a shortcut to educational equity.

NCEA does not guarantee even the most basic education. Nowadays, it is possible to pass it with flying colours, all the way to Level 3, without ever completing a standard in English or maths. And sure enough, this is what many students do.

In 2014, the Tertiary Education Commission appointed Victoria University to test the basic skill levels of our upper secondary students. The commission found that among a representative sample of 800 Year 12 students with NCEA Level 2, 40 per cent were functionally illiterate and 42 per cent functionally innumerate.

To be clear, this was not a test of whether students could analyse Shakespeare or solve quadratic equations; rather, it assessed whether students could answer simple comprehension questions about, for example, a job advert, and do basic calculations.

And this irksome finding reflects in New Zealand's PISA (Programme for International Student Assessment) statistics. From an impressive start in the early 2000s when the OECD began collating data, our performance has plummeted.

Between 2003 and 2015, the average maths performance of Kiwi 15-year-olds fell by the equivalent of almost a year of learning. In the 15 years to 2015, average reading performance fell by two-thirds of a year. These drops are dramatic, and coincide with the introduction of NCEA.

It is time we acknowledged that despite its wide-eyed aspiration, the system dampens expectations.

NCEA's inherent problems were so evident to some schools that they opted out from the beginning, in favour of other international qualifications. At last week's Cambridge Assessment International Education's conference in Auckland, educators debated the different incentives and expectations inherent in the two qualifications.

They regret the perverse incentives rooted deep in our national qualification, and are concerned for the direction of the current review.

Reluctance to raise minimum requirements stems from a righteous desire not to exclude anyone from succeeding. But what is the point of a certificate, if you still cannot read or write?

By setting the bar so low, we communicate the flawed belief that many children can never be literate or numerate. And this is simply untrue. The proportion of children who cannot master these skills is tiny.

Problems of literacy and numeracy are usually born in primary schools, if not even earlier in the home. It is no doubt unfair to hold secondary schools accountable for generating functional school leavers, when they have so little control over their intakes. But the solution lies in higher expectations throughout the system, not a certificate that masks the problem.

Schools can overcome illiteracy, and a higher bar would communicate priorities down the education chain.

So after 15 years of falling performance, will this year's review double down on NCEA's inclusivity through low expectations? Or will it trade some of NCEA's immense flexibility in favour of more meaningful success? The latter requires political courage, but is the only solution to our mess.