Sickness and short-term medical leave are likely heavy contributors to recent statistics showing more than half of students aren't regularly attending school, the Secondary Principals Association has revealed.

Education Ministry data shows 47 per cent of students regularly going to school in term two, down from 59.5 per cent in term one.

The figure was just 40 per cent in term two last year.

However, as principals association president, Vaughan Couillault explained on the Mike Hosking Breakfast, the threshold for a student to be considered a regular attendee needs to be taken into account.

Currently, a student must go to 90% of their classes to be considered regularly in school.

"As soon as you're sick for a week then you don't meet that threshold," said Couillault.

"So, it is very high and there is some debate over whether it's too high, but at the end of the day it is what we've got - it's how we weigh and measure ourselves."

When comparing statistics with term 2 last year, Couillault said it's important to measure like with like - the first term of the year will bring less cold and flu sicknesscompared to term 2 and 3 when sickness and flu symptoms begin to present much more commonly.

"And so, an improvement on term two last year is really what you need to measure against," said Couillault.

"But there is still a heck of a lot of work to do in this space."

Couillault said he was keen to drill down on the figures further to determine how many students were in school 88% of the time, given many students would struggle to meet the 90% mark but likely hit around 80%.

Year 12 and 13 also needed to have aspects like study leave taken into account for attendance numbers.

"When you dig into those stats a bit further, the most significant contributor to their absence is illness - not people wagging and not wanting to be at school," said Couillault.

Couillault told Hosking schools should aim for “well north of 50 per cent” when taking their students' leave into account, with the aim of reaching the 70% mark.

In February, Education Minister Jan Tinetti announced a $74 million package to increase resources for Attendance Services and fund 82 new attendance officers to work with at-risk students, their parents and schools.

Last year the Ministry of Education launched an attendance and engagement strategy with 13 priorities to increase attendance and engagement.

By 2026, the ministry wants to increase the number of children attending regularly to 75 per cent.