Standardised Age Scores (SAS) are a useful metric for determining a child's exam results, accounting for the different ages children might be when sitting the same exam.
Read on to find out what they mean, how they’re calculated, and how to use them.
What are standardised age scores?
Standardised age scoring (SAS) is used in most 11+ exams. It's a way to remove variables from test scores to compare results fairly. SAS ensures children aren't disadvantaged based on when they were born in the year.
Why are scores age-standardised?
Two children in the same school year can be almost a year apart in age, giving the older child a big advantage. To balance this out and even their chances, younger pupils are given extra marks.
For example, children are exposed to more than 1,000 new words a year. The children born in September will have had a much larger opportunity to develop their vocabulary than those born in August.
Younger children can gain marks, but older children will never lose marks.
How are standardised age scores calculated?
Each child’s SAS is calculated from:
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The number of questions they answered correctly
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The difficulty of the questions they answered
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Their age in years and months (e.g. 10 years and 9 months)
1. Attainment estimate
The first step in calculating an SAS is to work out an attainment estimate. This takes into account both the number of questions answered correctly and the difficulty of each question they answered correctly.
2. Age standardisation
Next, these scores are adjusted based on the child's age at the time they sit the exam. For example, let's say a child with a September birthday and a child with an August birthday both achieve a raw score of 100. The older child may end up with an SAS of 118, and the younger may be given an SAS of 121.
Find more detail below about the accuracy of SAS on Atom.
What's a good, low or average SAS?
- 80 or below is the lowest 10% of the year group
- 100 is the average SAS for the year group
- 120 or above is the top 10% of the year group
The highest SAS a child can achieve is 142 on an Atom test. This score would place them in the top 1% of children who took the test.
Using SAS on Atom School
We give your students an SAS for each mock test they complete on Atom School. This is the same scoring system used in the real exam, so it’s the best way to know what to expect.
Students' scores are standardised against other students in UK prep schools who have sat the same assessment, meaning the SAS is an accurate reflection of the score a student can expect to achieve in the real examination.
The student's SAS tells you how they're likely to perform on the real exam, at their current level of knowledge. Keeping an eye on how their SAS develops over time will give you insights into their progress.
What SAS should our students aim for?
If your student is applying for selective schools, aim for an SAS of at least 115 by the time they’re ready to take the 11+.
For more competitive grammar or independent schools, aim for an SAS of 120 and above.
If they're not applying to a selective school, use the SAS as a general indicator of their progress. An SAS of 112 or above tells you they're working above average for their year group and are in a strong position to take their next steps, such as starting secondary school.
SAS accuracy on Atom
How do you make sure your scoring is accurate?
Every year, children complete hundreds of thousands of tests on Atom. This gives us a rich, growing data set that helps us keep our scoring as close to real exam outcomes as possible.
After each exam season, we add results from around 700,000 completed tests. This ongoing expansion, combined with regular feedback from educators, means we’re always improving the accuracy and reliability of our scoring.
We standardise students’ scores against those of children at UK prep schools who’ve taken the same assessments. This means each Standardised Age Score (SAS) is a realistic reflection of how a student will perform in the actual exam.
My student's SAS on Atom is very different to their CAT4 SAS. Why is this?
You may notice that students often score slightly lower in Atom mock tests compared to national assessments like the CAT4. On average, a student’s Standardised Age Score (SAS) on Atom will be around 8–12 points lower than on the CAT4.
This is because Atom’s SAS is benchmarked against a high-performing cohort - students at independent prep schools across the UK and abroad. As a result, the ‘average’ score on Atom reflects a higher level of performance than the national average.
For example, if a student scores 108 on the CAT4, they might score closer to 100 on an Atom mock, even with the same raw score. This doesn’t mean they’ve done worse - it simply reflects the strength of the cohort of students preparing for independent school examinations.
The good news is that Atom’s scoring is carefully standardised each year using data from hundreds of thousands of test results. This means your students' mock scores are compared against the same type of cohort they’ll face in the real exam. Our approach gives you a realistic, up-to-date picture of how your students are likely to perform in their upcoming examinations.
My student only got one question wrong, but their SAS is only 130. Shouldn't it be higher?
Standardised age scores are mapped onto a distribution curve. An SAS of 100 places a child as exactly average for their year group. A score of 120 or above places a child in the top 10% of their year.
Only the top 4% of children achieve an SAS of 130+, and the top 1% achieve a score of 140–142. Standardised scores don't correspond directly to raw scores – they're calculated using factors such as the child's age and performance compared to peers.
If your child achieved an SAS of 130, this puts them in the top 4%. It shows that around 4% of children only answered one question incorrectly in this test.
My student got a different SAS on two tests even though they got the same number of correct answers. Why?
There are a few reasons why a child might get a different SAS despite the same raw score. SAS is based not just on how many questions were answered correctly, but also:
- The difficulty of the questions answered correctly
- The child's age in years and months.
On the test where they got a higher SAS, your students likely answered more difficult questions correctly.
If one or both of the tests were adaptive (like ISEB), the SAS is further impacted by any mistakes made early in the test. When taking an adaptive test, accuracy is key. Each answer will impact the difficulty of the questions your student sees later in the test.
- If a child gets easy questions correct, the test will show them more difficult questions. This gives them a greater opportunity to achieve a high SAS.
- Conversely, if a child gets easier questions wrong, the test will keep showing them easier questions until their accuracy improves.
Lastly, if your student is practising for multiple exams, you can expect them to achieve a different SAS in different types of test. This is because each SAS is calculated against other children who took the same test. The same raw score could place your students in an average position in one cohort, but above average in another cohort.
What is the highest/lowest SAS my students can achieve?
The highest SAS your students can achieve in an Atom mock test is 142, the lowest is 58. A score of 100 is average.