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nm

I gather your child is nine years old?

Yes, the possible standard score for that subtest component at that age tops out at 134. The Sentence Combining component tops out at 144, and the whole Sentence Composition subtest has a maximum obtainable score of 149.

The short answer is that these are the limits of the instrument. Statistically, one doesn't often need standard scores higher than that. (BTW, the same issue exists for the floor of this particular subtest: the lowest obtainable component score for SB at this age is 55, and the lowest possible subtest score is 56.) Test designers have to balance range, sensitivity, reliability, psychometric robustness, etc. with usability. One could design a test with a higher ceiling, but it would probably need more items. Since Sentence Composition is administered in its entirety to every student in its age/grade range (age 6+/grade 1+), the additional length would benefit less than 1% of students, but would increase factors related to test length and fatigue for 100% of students. This is not as much of a factor for subtests with more traditional number-of-items-incorrect-in-a-row discontinue critera as it is for subtests with item sets, like SC and Reading Comprehension.

aeh,

So this also applies to the WISC-V test, correct? My DS6 took the test and he got three scaled scores of 19 out of the 10 subtests. The tester said that 19 is the max and he did not have more questions for him to answer. Dose this mean that if my DS was given more difficult questions, it's possible that he would have received higher scores and therefor higher FSIQ score?

Thank you

aj,

Same general idea, but not exactly the same. The max score of 19 on the WISC-V is the actual max possible scaled score (+3 SDs) on any subtest, at any age, on the test. In standard score terms, these would be equivalent to 145. (This is not the case in the OPs situation, where the equivalent max is +4 SDs, or standard score 160.) The tester was actually telling you a few separate pieces of information. 19 is the max, even if he had had more questions to answer, because the norms are only built out to +3 SDs. In order to receive a higher set of index scores, he would have needed extended norms (i.e., a higher-level comparison group, such as was developed for the WISC-IV and SBV). It is possible that, even with extended norms, he would also have needed additional items, if he did not reach a natural ceiling on those subtests (i.e., trigger the discontinue rules), though in your DC's case, his young age suggests that he had ample data for calculating extended index scores (if such existed at this time). The expectation appears to be that extended norms for the WISC-V will be developed at some point in the near- or mid-term, so I would make sure you have access to all the raw scores, in case the extended norm tables are released in the future.

When I have students who don't reach natural ceilings on tests that lack extended norms, I generally comment in my eval report that these are possible low estimates of ability.

ETA: Actually, I'm reading now that the WISC-V extended norms have an anticipated release date of late this year.

The psychologist who administered the test allowed me to take a picture of the score sheet which contains the raw scores. My DS did not reached the natural ceiling on those subtests. I will be sure to ask questions on how to figure out the extended index scores when the extended norm becomes available for WISC-V.

Thank you so much for your explanation and clarification.

nm