Raw scores are converted into scaled scores using the age-based norm tables. Some cognitive skills have known population profiles vs age (e.g., working memory and fluid reasoning reach peaks in the early 20s), so finding an individual's standing among age-peers requires using age norms. Raw scores apply only to scaled scores for subtests.

Index scores (FSIQ, GAI, VCI, PRI, WMI, PSI) are determined by taking the sum of the relevant subtest scaled scores and converting them to standard scores using the composite score tables, which are not additionally age-normed. (All ages use the same conversion charts.)

For example, say you get a raw score of 9 (meaning you received credit for the first nine items on the task) on Arithmetic (again, none of these are real numbers, as I don't have the tables in front of me). You go to the age-norm tables, and find that, at your age, that converts to a scaled score of 8. After you obtain scaled scores on all of your subtests, you add them up and (say) get a sum of scaled scores of 90. When you take this to the FSIQ charts, this comes out as a standard score of 95, in the Average range. We then say your IQ is 95.


...pronounced like the long vowel and first letter of the alphabet...