Question
What is a scaled score?
Short answer
A scaled score is the score for one subtest on tests like the WISC-V. It uses a mean of 10 and a standard deviation of 3, ranging from 1 to 19, and 8 to 12 is typically considered average. Scaled scores are combined into index scores and the Full Scale IQ, which use mean 100 and SD 15.
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Two scales on one report
Clinical intelligence reports use two kinds of standard scores. Each subtest gets a scaled score with a mean of 10 and a standard deviation of 3, from 1 to 19, with 8 to 12 typically considered average. The index scores and the Full Scale IQ use a mean of 100 and a standard deviation of 15 (Pearson: WISC-V UK sample report). The numbers look different, but both describe the same thing: how far a result sits from the average for the person's age.
Converting between them
| Scaled score | Matching standard score | SDs from the mean |
|---|---|---|
| 4 | 70 | -2 |
| 7 | 85 | -1 |
| 10 | 100 | 0 |
| 13 | 115 | +1 |
| 16 | 130 | +2 |
The conversion is just arithmetic on standard deviations. Because both scales follow the normal curve, about 68% of people fall within one standard deviation of the mean on either one: scaled scores of 7 to 13, or standard scores of 85 to 115 (the 68-95-99.7 rule).
Try one · Logical Reasoning
Which tile completes the second pair?
Tap the option you think is right, or show the answer.
Show the answer
The missing panel shows a large outlined circle, with small solid shapes: a triangle at the left side (option 1).
How to solve it
- Compare the first two panels and name exactly what changed.
- The main shape and the small shapes swap forms: the main shape takes the form of the small ones, and the small ones take the form of the main shape.
- Nothing else changes.
- Apply the same change to the third panel: a large outlined triangle pointing up, with small solid shapes: a circle at the left side.
- So the missing panel shows a large outlined circle, with small solid shapes: a triangle at the left side.
That was 1 puzzle. The full test has 25.
Reading subtest scores sensibly
- One subtest is a small sample of behavior, so a single low or high scaled score is weak evidence on its own.
- Patterns across subtests and indexes say more than any one number.
- Composite scores pool several subtests, which is why they carry more weight than any single subtest.
Related
See what a Full Scale IQ is, the WISC-V, z-scores and standard deviation. For IQ-scale percentiles, try the IQ percentile calculator.
Sources
- Pearson Clinical UK. WISC-V UK sample interpretive report (Q-global). 2016. www.pearsonclinical.co.uk/content/dam/school/global/clinical/uk-clinical/files/wisc5-sample-interpretive-report.pdf
- 68-95-99.7 rule. Wikipedia. en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule