You open the report and find tables full of numbers. Sound familiar? A psychological report is a dense document, and the numbers in it are unlike any others parents encounter. Here is a short guide to reading yours without misreading it.
What is a standard score?
Most composite scores (full-scale IQ, index scores, reading and maths composites) use a scale where the average is set at 100 and one standard deviation is 15 points. In practice:
Individual subtests on the WISC-V use a different scale, where 10 is average and 7 to 13 is the typical range. If you see a “9” next to a “104”, they are not contradictory. They are simply two different rulers. Reports should always say which scale is in use.
What is a percentile rank?
A percentile rank of 25 means that out of a hundred children of the same age, roughly 25 scored lower and 75 scored higher. It is not a percentage of questions answered correctly! This is the single most common misreading. The 50th percentile is exactly average, which is a perfectly good place to be.
Percentiles are also unevenly spaced. The difference between the 45th and 55th percentile is a couple of standard-score points; the difference between the 1st and 5th is much larger in real terms. Near the middle, small movements mean very little.
Why is a score really a range?
You will see something like “104 (95% CI: 98–110)”, where CI stands for confidence interval. No test measures with perfect precision, so the honest statement is a band rather than a point. Read the band, not the number. Two scores whose bands overlap heavily are not meaningfully different, however tempting it is to say one is “better”.
Why is the overall IQ figure often the least useful number?
A full-scale IQ is an average of quite different abilities. When those abilities are uneven (the very reason most children are referred), the average describes nobody. For example, a child with verbal reasoning at the 91st percentile and processing speed at the 6th may produce a full-scale score of 100, “perfectly average”, which conceals the two facts that actually explain their school life. Good reports say so explicitly, and direct your attention to the index scores instead.
What should you read first?
Here is the order: the summary and formulation first, which tell you what it all means; then the recommendations, which tell you what to do; and only then the tables, to see the evidence. Reading the tables first is how parents frighten themselves unnecessarily.
And bring your questions back. A report you do not understand cannot help your child; asking the psychologist to explain a section again is entirely normal and part of the work.
100 is average, 85 to 115 is the ordinary range, a percentile counts children rather than marks, and the shape of the profile tells you more than any single score. The numbers are only the starting point. What matters is what you do with them.