What do New Zealand students understand about civic knowledge and citizenship?

Publication Details

This is the first of a series of publications based on the results of the International Civic and Citizenship Education Study (ICCS). This report focuses on New Zealand Year 9 students' achievement in civic knowledge in comparison with their peers from other countries.

Author(s): Kate Lang, Research, Ministry of Education.

Date Published: November 2010

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Definitions and technical notes

ICCS cognitive scale scores

The ICCS cognitive scale was derived from 79 test items, and set to a metric with a mean of 500 (the ICCS average score) and a standard deviation of 100 for equally weighted national samples.

Means and averages

The mean of a set of scores is the sum of the scores divided by the number of scores, and is also sometimes referred to as ‘the average’. Note that for ICCS the means are adjusted slightly (in technical terms, ‘weighted’) to reflect the total population of Year 9 rather than just the sample.


The lowest reported achievement is for the 5th percentile – the score at which only 5 percent of students achieved a lower score and 95 percent of students achieved a higher score. The highest reported achievement is for the 95th percentile – the score at which only 5 percent of students achieved a higher score and 95 percent of students a lower score; thus 90 percent of student scores lie between the 5th and 95th percentile.


Schools were sampled with equal probability of selection. To improve the precision and representativeness of the sample, schools were grouped by size (very large schools with 330 or more Year 9 students and all other schools), decile, type of school (co-ed, single-sex girls and single-sex boys) and state-funded/ private, then sorted by the number of Year 9 students at each school. Within each school, classes were sampled with equal probability and all Year 9 students within each class were selected. The final sample was representative of the New Zealand Year 9 student population.

Statistical significance

It is usual to undertake significance tests to determine whether differences between two averages are actual. These tests take into account the means and the error associated with them. If a difference is not statistically significant then we do not have enough evidence to infer that they are different. All significant differences reported in this publication are at the 95 percent confidence level. Note that it is not possible to test for statistical significance if the two groups being tested are not mutually exclusive (e.g. total response ethnic data, where students who identified with more than one ethnic group are counted in each group).

Standard error

Because of the technical nature of ICCS, the calculation of statistics such as means and proportions has some uncertainty due to (i) generalising from the sample to the total Year 9 school population, and (ii) inferring each student’s proficiency from their performance on a subset of items. The standard errors (usually given in brackets) provide a measure of this uncertainty. In general we can be 95 percent confident that the true population value lies within an interval of 1.96 standard errors either side of the given statistic. The confidence interval is represented in graphs by the lines extending in either direction from the data points.

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