Parts and whole
5 August 2013
The importance of being wrong
19 August 2013

NCEA League tables in the newspaper

My husband ran for cover this morning when he saw high school NCEA (National Certificates of Educational Achievement)  league tables in the Press. However, rather than rave at him yet again, I will grasp the opportunity to expound to a larger audience. Much as I loathe and despise league tables, they are a great opportunity to teach students to explore data rich reports with a critical and educated eye.  There are many lessons to learn from league tables. With good teaching we can help dispell some of the myths the league tables promulgate.
When a report is made short and easy to understand, there is a good chance that much of the ‘truth’ has been lost along with the complexity. The table in front of me lists 55 secondary and area schools from the Canterbury region. These schools include large “ordinary” schools and small specialist schools such as Van Asch Deaf Education Centre and Southern Regional Health School. They include single-sex and co-ed, private, state-funded and integrated. They include area schools which are in small rural communities, which cover ages 5 to 21. The “decile” of each of the schools is the only contextual information given, apart from the name of the school.  (I explain the decile, along with misconceptions at the end of the post.) For each school is given percentages of students passing at the three levels. It is not clear whether the percentages in the newspaper are of participation rate or school roll.
This is highly motivating information for students as it is about them and their school. I had an argument recently with a student from a school which scores highly in NCEA. She was insistent that her friend should change schools from one that has lower scores. What she did not understand was that the friend had some extra learning difficulties, and that the other school was probably more appropriate for her. I tried to teach the concept of added-value, but that wasn’t going in either. However I was impressed with her loyalty to her school and I think these tables would provide an interesting forum for discussion.

Great context discussion

You could start with talking about what the students think will help a school to have high pass rates. This could include a school culture of achievement, good teaching, well-prepared students and good resources. This can also include selection and exclusion of students to suit the desired results, selection of “easy” standards or subjects, and even less rigorous marking of internal assessment. Other factors to explore might be single-sex vs co-ed school, the ethnic and cultural backgrounds of the students, private vs state-funded schools.  All of these are potential explanatory variables. Then you can point out how little of this information is actually taken into account in the table. This is a very common occurrence, with limited space and inclusion of raw data. I suspect at least one school appears less successful because some of the students sit different exams, either Cambridge or International Baccalaureate. These may be the students who would have performed well in NCEA.

Small populations

It would be good to look at the impact of small populations, and populations of very different sizes in the data. Students should think about what impact their behaviour will have on the results of the school, compared with a larger or smaller cohort. The raw data provided by the Ministry of Education does give a warning for small cohorts. For a small school, particularly in a rural area, there may be only a handful of students in year 13, so that one student’s success or failure has a large impact on the outcome. At the other end of the scale, there are schools of over 2000, which will have about 400 students in year 13. This effect is important to understand in all statistical reporting. One bad event in a small hospital, for instance, will have a larger percentage effect than in a large hospital.

Different rules

We hear a lot about comparing apples and oranges. School league tables include a whole fruit basket of different criteria. Schools use different criteria for allowing students into the school, into different courses, and whether they are permitted to sit external standards. Attitudes to students with special educational needs vary greatly. Some schools encourage students to sit levels outside their year level.

Extrapolating from a small picture

What one of the accompanying stories points out is that NCEA is only a part of what schools do. Sometimes the things that are measurable get more attention because it is easier to report in bulk. A further discussion with students could be provoked using statements such as the following, which the students can vote on, and then discuss. You could also discuss what evidence you would need to be able to refute or support them.

  • A school that does well in NCEA level 3 is a good school.
  • Girls’ schools do better than boys’ schools at NCEA because girls are smarter than boys.
  • Country schools don’t do very well because the clever students go to boarding school in the city.
  • Boys are more satisfied with doing just enough to get achieved.

Further extension

If students are really interested you can download the full results from the Ministry of Education website and set up a pivot table on Excel to explore questions.
I can foresee some engaging and even heated discussions ensuing. I’d love to hear how they go.

Short explanation of Decile – see also official website.

The decile rating of the school is an index developed in New Zealand and is a measure of social deprivation. The decile rating is calculated from a combination of five values taken from census data for the meshblocks in which the students reside. A school with a low decile rating of 1 or 2 will have a large percentage of students from homes that are crowded, or whose parents are not in work or have no educational qualifications. A school with a decile rating of 10 will have the fewest students from homes like that. The system was set up to help with targeted funding for educational achievement. It recognises that students from disadvantaged homes will need additional resources in order to give them equal opportunity to learn. However, the term has entered the New Zealand vernacular as a measure of socio-economic status, and often even of worth. A decile 10 school is often seen as a rich school or a “top” school. The reality is that this is not the case.  Another common misconception is that one tenth of the population of school age students is in each of the ten bands. How it really works is that one tenth of schools is in each of the bands. The lower decile schools are generally smaller than other schools, and mostly primary schools. In 2002 there were nearly 40,000 secondary students in decile 10 schools, with fewer than 10,000 in decile 1 schools.


  1. Jacinta says:

    Really interesting discussion! The Education Counts website run by the Ministry of Education is probably a better source of information for people wanting more detailed achievement information, though: Lots of really interesting stuff there!

  2. mpledger says:

    The other thing about league tables is that they never display the error on the rank e.g. rank 1, 95% CI (1-3). Often the error in the ranks can be much larger than you would think and that’s before you adjust for all the biases caused by non-random allocation of students to schools.

  3. bonny ranfurly says:

    great stuff Nic

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