What is a Standardised Score?

A Standardised Score is a way of making scores achieved on tests comparable to each other and over time. For example, three children may take three different standardised tests in reading. All three tests measure reading ability  but the first test is out of 50, the second out of 70 and the third out of 60. 

It would be difficult to compare scores of these three children as the scales (The total marks available on each test) are different. 

Using a standardised score it is possible to compare the scores across tests and to compare performance over time.

When using Standardised Scores 100 is the average score, however, a number of factors can affect a child’s performance when taking a test. For example on the day of the test Child A might have had an awful night’s sleep, Child B may be looking forward to their birthday party later on in the day whilst Child C has had a good night’s sleep and has few factors affecting their performance. In this way we can only ever say that a test is a snapshot of a child’s attainment as it would be theoretically possible for a child to take the same test on different occasions and achieve different scores. 

When interpreting Standardised Scores the following chart is helpful:

Interpreting a Child’s Standardised Score an example:

Reading Test	2021	2022	2023
Child A	96	100	103
Child B	85	94	100

In the example above Child A’s standardised score differs slightly, but their attainment would be seen as average.

In the case of Child B in the standardised scores in 2021 and 2022 would be seen as in the low average range. However their standardised score of 2023 would be seen in the average range. As these are snapshots it would be possible to say that Child B’s attainment has improved but would need to be seen in context with Child B’s teacher assessment and performance across the year.