Statistical data about primary and secondary schools and their students can be broken down into socio-economic deciles. For example, data released by the Ministry of Education shows there is a correlation between high decile schools and higher rates of attaining NCEA Level 2,[3] higher rates of tertiary education entrance,[4] and lower rates of truancy.[5]
Analyses of mathematics achievement for students in schools in each decile band demonstrate that mathematics achievement is higher in higher decile schools and lower in lower decile schools as shown in Figure:
There is a clear positive correlation between the socio-economic mix of the school the student attended and the percentage of school leavers achieving a university entrance standard. Schools in the lowest deciles (deciles 1 and 2) draw their students from communities with the highest degree of socio-economic disadvantage. Students from schools in the highest deciles (deciles 9 and 10) are 2.6 times more likely to leave school having achieved a university entrance standard than students from schools in the lowest two deciles. There is a great deal of variation amongst schools within each decile. (请注意这最后一句话。这句话的意思是说,都是同样Decile分数的学校,统计出来的结果会有很大的差异。但是整体上的统计规律依然是可以从下图中明确的体现出来的。)