The 20 per cent tail is, in fact, spread all over the country and all schools have a part of the tail.
Let us begin by dispelling the first myth: the groundless generalisation that the students are not gaining qualifications.
The advent of NCEA has meant students can build a qualification which has resulted in a significant improvement in student retention from Year 11 to 13 in decile one schools.
Ministry of Education figures show that for Otahuhu College we now retain students at a rate slightly better than decile-8 schools.
This means we have significantly more students in our senior school, but are we getting them qualifications?
The answer is yes.
The number of students leaving with little or no formal attainment has dropped significantly over the past five years to the decile six average while numbers of leavers with less than Year 12 qualifications have also declined markedly over the same time.
Our percentage of Year 13 leavers with a Year 13 qualification has also risen.
We still struggle at level one because of the 80 credits needed but improved retention has meant that many of our students complete level one NCEA in Year 12 and then level two in Year 13.
Unfortunately, we cannot get enough to return for a Year 14 to really give our level three results a kick along.
The second myth centres around what is being offered as senior curriculum in low- decile schools.
Often it is said that low-decile schools are not running enough practically based courses.
At Otahuhu, we run automotive engineering, carpentry, fine furniture and hospitality while at the same time having a number of academies.
These include a sports academy and service academy for students interested in these areas.
Last year, we saw the introduction of a health sciences academy for students who wish to pursue a career in this area when they leave school.
This year, this will contain 50 students with a real focus on physics, chemistry and biology.
Contrary to the belief of many we have workshops, a catering kitchen and are looking to increase the number of science laboratories we have because of the increased number of our students opting to take science.
Gateway - a Tertiary Education Commission-funded programme - is proving very successful at the college with the students gaining valuable work experience and starting to see the connection between their studies and the world of work.
We have received a significant increase in funding for this programme this year and hope to grow the number of apprenticeships our students get. Levels of co-operation from employers are playing a major part in the success of this programme.
The great news for this year is that eight of our students will begin apprenticeships.
The next step in this area that would make a significant difference would be for all our students to leave school with a full driver's licence as so many employers insist on a full licence as a condition of employment. Cost is the biggest barrier here.
The third myth out there is that low-decile schools have trouble recruiting staff.
This is not the case in South Auckland.
I have had the privilege of working with many superb staff and have also been able to recruit excellent graduates from the University of Auckland teacher training programme.
Recruitment is only an issue when there are shortages in a particular subject area across the country or when teacher supply is low.
At the moment there are wonderful young graduates wanting to teach in our schools but there are no jobs for them.
My plea to all commentators on education is: visit your local high school and see what is happening rather than relying on hearsay or your own experiences of school possibly many years ago.
Low-decile schools contain dedicated teachers and ancillary staff who are working incredibly hard to raise levels of achievement and to ensure their pupils leave with a meaningful qualification that will assist them to gain entry into the workforce or further training.
Come along and be part of the solution.