Definition
A standardised score compares a child's performance to a representative sample of same-aged peers. The standardised scores used in UK educational and clinical assessment have a mean of 100 and a standard deviation of 15, with around 68% of children scoring between 85 and 115, and around 95% between 70 and 130. Scores below 70 or above 130 are statistically unusual.
In context for parents
Key checkpoints
- A standardised score compares a child's performance to a representative sample of same-aged peers.
- UK standardised scores have a mean of 100 and standard deviation of 15.
- ~68% of children score 85–115; ~95% score 70–130; below 70 or above 130 is statistically unusual.
- WISC-V, WIAT-III UK, CELF-5 UK, BPVS-3, and Movement ABC-2 all use the 100/15 scale.
- Standard error of measurement (±3–5 points for major tests) means scores should be thought of as a range, not a precise number.
Standardised scores are the language of cognitive, language, attainment, and motor assessment in UK SEND. The WISC-V, WIAT-III UK, CELF-5 UK, BPVS-3, and Movement ABC-2 all use the 100/15 standardised scale (or in some cases a scaled-score scale with mean 10, SD 3 for subtests, with index scores converted to 100/15).
The interpretive bands most often used in EP and SaLT reports:
- Above 130: very superior / well above average (top ~2%)
- 120–129: superior (next ~7%)
- 110–119: high average
- 90–109: average (middle ~50%)
- 80–89: low average
- 70–79: borderline (bottom ~7%)
- Below 70: extremely low / well below average (bottom ~2%)
The distinction between a standardised score of 87 and 84 may not be clinically significant, both fall within the broad "low average" band. The distinction between 89 and 69 is large: the first is broadly age-typical; the second indicates a significant difficulty. The standard error of measurement (typically ±3–5 points for major tests) means parents should think of scores as a range rather than a precise number.
What a standardised score does not tell you:
- It does not tell you what to do.
- A child with a standardised score of 72 on Working Memory needs a Working Memory profile: what specific subtests dropped, what compensatory strategies are working, what functional impact this is having.
- The standardised score is a starting point for intervention design, not the destination.
For an EHCP, standardised scores frequently feature in Section B as the evidence for the named area of need. A child with multiple standardised scores at or below 70 across cognitive, language, and attainment measures presents a different SEND picture from a child with one isolated score in that range.
Related terms
The terms parents most often see alongside Standardised Score.
Centile
A percentile rank showing the percentage of same-age children who would score lower than the child being tested. A 5th centile score means 95% of peers scored higher.
Wechsler Intelligence Scale for Children(WISC)
A widely used standardised assessment of cognitive ability for children aged 6-16, producing index scores for verbal comprehension, visual-spatial, fluid reasoning, working memory, and processing speed.
Wechsler Individual Achievement Test(WIAT)
A standardised assessment of academic attainment in reading, writing, maths, and oral language, commonly used to identify specific learning difficulties.
British Picture Vocabulary Scale(BPVS)
A standardised, untimed test of receptive vocabulary in children. The child points to one of four pictures matching a spoken word, useful for children with limited expressive language.
Where parents ask about this
Parents usually find this page after an EP or SaLT report has reported standardised scores and parents want to understand what they mean. Searches include "WISC standardised score 85", "what is a normal standardised score", and "standardised score interpretation SEND". A Beaakon EP or SaLT can carry out a full assessment, interpret standardised scores in the context of your child's functional picture, and write a tribunal-grade report.
References
The primary legislation, statutory guidance, research, and clinical tools this page draws on.