In educational assessment, a stanine (short for STAndard NINE) is a method of scaling test scores on a nine-point standard scale with a mean of 5 and a standard deviation of 2.
It is designed to simplify the interpretation of test results by grouping scores into broad categories rather than looking at precise raw scores or percentiles.
How Stanines Work
The scale converts a normal distribution of scores into nine units.
| Stanine | Percentage of Cases | Performance Level |
| 9 | 4% | Highest (Top) |
| 8 | 7% | Well Above Average |
| 7 | 12% | Above Average |
| 6 | 17% | High Average |
| 5 | 20% | Average |
| 4 | 17% | Low Average |
| 3 | 12% | Below Average |
| 2 | 7% | Well Below Average |
| 1 | 4% | Lowest (Bottom) |
Key Characteristics
Coarseness: Because it only has nine points, it "smooths out" small, insignificant differences between students. For example, two students with slightly different raw scores might both be a "Stanine 6," preventing over-interpretation of minor score gaps.
Comparison: It allows educators to compare a student’s performance across different subjects (e.g., comparing a Stanine 7 in Math to a Stanine 5 in Reading) using a single, unified metric.
Simplicity: It is often easier for parents and students to understand than complex z-scores or T-scores.
Mathematical Context
If you are working with standard normal distributions, the stanine (S) can be calculated from a z-score (z) using the following linear transformation:
The result is then rounded to the nearest whole number between 1 and 9.
Use in Pedagogy
In the context of Outcome-Based Education (OBE) or curriculum design, stanines are frequently used to identify groups of students who may need additional support or advanced enrichment, as they provide a clear snapshot of where a student sits relative to a peer group.
Would you like me to help you create a grading rubric or a distribution chart based on this scale?
--Gemini
