What are stanines?

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Stanines are rankings, from 1 to 9.  Stanines can be used to compare a test result from a student in a particular year level at your school with the typical performance of Australian students in that same year level. 

The norm distribution at each year level is divided into 9 groups based on the standard deviation of a normal distribution – the standard nine.  

Thee word ‘stanine’ comes from ‘standard nine’ and is where the normal distribution is divided into nine sections that have an equal width, except for the first and last which contain the tails of the distribution. This results in each section containing a different proportion of the population.

  • Stanine 1 contains the proportion of students with the lowest test scores, up to the 4th percentile.
  • Stanine 2 contains the next 7% of test results, up to the 11th percentile. 
  • Stanine 3 contains the next 12% of test results, up to the 23rd percentile.
  • Stanine 4 contains the next 17% of test results, up to the 40th percentile.
  • Stanine 5, in the middle of the distribution, contains the next 20% of test results, up to the 60th percentile.
  • Stanine 6 contains the next 17% of test results, up to the 77th percentile. 
  • Stanine 7 contains the next 12% of test results, up to the 89th percentile. 
  • Stanine 8 contains the next 7% of test results, up to the 96th percentile.
  • And Stanine 9 contains the top 4% of test results.

Stanines provide rankings but do not provide a reliable or useful measure of students’ learning growth.

Consider a situation where a student completed the Year 2 assessment last year, achieved a scale score of 122, a percentile of 90 and was placed in stanine. This year, the student in Year 3 completed an assessment, achieved a scale score of 128.0, a percentile of 87 and was placed in stanine 7.  

Does this mean the student went backwards because a lower stanine was achieved in Year 3? The answer is ‘no’. If a student’s scale score has increased, then they have improved in their learning, regardless of their percentile or stanine rank which only compares them with the norm.

Consider a situation where Student A and Student B sit a PAT assessment in Year 5. The results place both students in stanine 4. The following year, the two students sit the Year 6 assessment and are both again placed in stanine 4.

The stanine values themselves only give us part of the story. We need to look at the students’ scale scores.

Both Student A and Student B have improved their scale scores from Year 5 to Year 6, but there has not been any change in their stanines. However, according to the scale scores, Student B has improved her scale score more than student A.

This example demonstrates that you cannot observe growth using stanine rankings.

To measure a student’s progress over time, we need to forget about stanines and look only at the student’s scale scores.

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