Standardised age scores (SAS) – all you need to know

All about standardised age scores – 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. 

Concerned that your autumn-born child will have marks taken off them? Don't worry, they won’t. 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:

• The number of questions they answered correctly

• The difficulty of the questions they answered

• 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 usually 142. This score would place them in the top 1% of children who took the test.

The distribution curve

SAS can be mapped onto a distribution curve. This shows how scores are distributed for a year group:

• Around 23% of children got a lower-than-average SAS (88 or below)
• Around 54% of children got an average SAS (89 to 111)
• Around 23% of children got a higher-than-average SAS (112 or above)

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Using SAS on Atom Home

We give your child an SAS for each mock test they complete on Atom Home. This is the same scoring system used in the real exam, so it’s the best way to know what to expect.

Your child'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 we aim for?

If your child 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 you're not applying to a selective school, use your child’s 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.

How do we improve my child’s SAS?

Your child’s mock test scores will grow over time, as long as they keep logging in to Atom Home for short learning sessions each week. Encourage your child to:

• Keep working through their weekly activities, answering the questions independently
• Use the videos and helpsheets to build their understanding

If you like, you can set extra practices to target the topics your child struggled with on a mock test. Your child’s exam prep plan will also target these areas automatically. 

By the time they next take a mock test, their understanding will have increased and they’ll be likely to achieve a higher SAS.

Your child can also improve their SAS by building their exam technique. By practising mock tests on Atom Home your child will get familiar with taking timed tests. They’ll get used to pacing themselves, which will let their knowledge shine.

My child is disappointed by their SAS

We want to give you the clearest data so you always know where you stand. But, we know that not every child will like to see that they have scored ‘below average’. Your child should be proud of their effort and progress, not discouraged by a lower-than-average SAS.

Reassure your child there are many reasons they may have scored ‘below average’ – from having an off day, to not being used to exam conditions, to simply needing more practice in those topics. Remind them that:

• A ‘below average’ SAS is not something to worry about. With regular practice, it’ll soon increase.
• The SAS is a snapshot of your child’s performance in one mock test. ‘Below average’ is only a statistical description of their score in this mock test. It’s not a description of their abilities, their hard work, or their potential.

Even if your child normally works above average in a subject, they might need to develop their exam skills before they can score highly in mock tests. For example, perhaps they find exam conditions daunting, or tend to rush the questions.

Take time to talk through your child’s results in a positive and encouraging way. Identify skills or topics they’d like to practise more and build confidence in.

I don’t want my child to see their SAS

You can password-protect your Track page so that your child can't see their scores. We recommend you do this if your child is likely to find their SAS demotivating or distracting.

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SAS accuracy on Atom

How do you make sure your scoring is accurate?

Each year, children complete hundreds of thousands of tests across Atom's platforms. This data allows us to ensure the scoring on our platform is as close to the real position as possible.

We're constantly improving our platforms to give parents, tutors and teachers access to the most useful, robust data. After each exam season, we expand our data set, adding data from ~700,000 completed tests. We seek regular feedback to make sure our scoring is as accurate as possible to the results achieved in real exams.

My child 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.

Learn more in this video.

My child 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 child 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 child 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 easy questions. They won't see the more difficult questions.

Lastly, if your child 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 child in an average position in one cohort, but above average in another cohort.