Wales numeracy test scores revised after miscalculation
Thousands of pupils' scores in a numeracy test will be revised because of a problem with the way the data was calculated.
The Welsh Government said "a minor issue" had emerged with the way the results were worked out to produce an "age-standardised" score.
The issue affects most of the 268,000 pupils in years 2 to 9 who took the online test.
They will see a "slight change" in their score, a spokesperson said.
Most pupils who scored above average will see their mark revised down and most who scored below average will be revised up.
This year's assessment of "procedural numeracy" - maths calculations - was the first to be taken online as part of changes to annual reading and numeracy tests.
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Online reading assessments in Welsh and English will be available to schools this autumn, before the "numeracy reasoning" test - solving maths problems - moves online from 2020.
The changes see the difficulty of questions change depending on the answers given by the pupils, with the aim of giving a more accurate picture of a child's progress.
The raw scores are then compared with other pupils who were born in the same year and month and then adjusted to take account of their age.
How will the scores change?
- Most pupils who took the tests will see a slight change in their score
- The average score is 100
- No pupil will cross from below 100 to above or vice versa
- The scores for most pupils who scored below 100 will rise a little - by at least one point, and by no more than eight points
- The scores for most pupils who scored above 100 will fall a little - by at least one point, and by no more than eight points
In a written statement to assembly members the Education Minister Kirsty Williams said the problem was not part of the automated system but had happened "offline" and that "additional checks" were now in place.
She added the revisions did "not affect the information provided on the skills of each individual learner, which is the primary purpose of the assessment; it is only a minor adjustment to the age-standardised score".
The Welsh Government said it had written to head teachers to inform them about the amendments and all schools would have the updated information by the start of October.
A spokesperson said it was up to schools to consider how the information is shared with parents and carers.
National reading and numeracy tests were introduced in 2013 for all pupils in year two to nine, after standard attainment tests (Sats) were ditched in Wales a decade earlier.
The Welsh Government says their purpose is to help teachers track pupils' performance and support their learning, and they are not a way to measure schools.
But they have proved controversial with some teachers claiming they place unnecessary pressure on young children and add little to teachers' understanding of pupils' attainment.
The Welsh Government has said that moving to a system of online personalised assessments will provide more meaningful feedback, while reducing teacher workload.