Gifted Issues Discussion homepage Forums Identification, Testing & Assessment question about WISC--hitting the ceiling

I was thinking about the WISC and wondering how it works if older kids are given the test, since it goes up through age 16. My DD who had just turned 8 when she took it got 18's-19's on a few of the sections--for instance Matrix Reasoning she apparently ran out of questions and answered two questions wrong. So wouldn't it be extremely easy for a bright 16 year old to hit ceilings on subtests if a 7 or 8 year old can do that?

Thanks for asking that - I have always wondered that myself as my DD@7 (almost 8 when she took it) ceilinged on several tests too.

Maybe they have different blocks to work with or entirely different and harder panels of questions?

Ceilings are ceilings relative to the tester age. The 19 point scaled score is derived from the raw score for a subtest based on the normal score.

As a pure example: A sub-section may have 40 progressively harder questions, an eight year old may hit the ceiling after getting 23 correct generating a scaled score of 19 (which is 3 standard deviations above the mean.)

A fourteen year old may get a scaled score of 19 with 38 correct.

For tests like WISC, all of the components and questions should availble and the only stopping point is based on them getting so many questions wrong in a row.

It's the same list of questions for every kid aged 6-16. It is age normed. For a 16 year old to score a 19 (i.e. +3sd) on a subtest (even with extended norms available) they basically need to get every question right.

I looked back at the report and it says she got right 31/35 for matrix reasoning, but I thought the tester told me after the test that she got 2 questions wrong and she ran out of questions (because I think they have to answer 3 wrong before the test is stopped). Maybe each is worth 2 points? I would love to see the test and see what was so hard that DD was actually answering that most 16 yo's wouldn't be able to answer.

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I don't know about the Matrix Reasoning subtest (hopefully someone will), but our tester mentioned 1 and 2 point answers for the Similarities subtest, so Matrix Reasoning may be similar. DS (6 1/2 at the time) answered all but one of the items with at least one point scoring, resulting in the discontinuation criterion not being met. As a result, the tester noted that the composite scores are likely to be underestimates.

I'm thinking it has to be something like that. Maybe they get one point for getting the right answer and one point for explaining it? I don't know. There can't be 35 matrix reasoning problems (or whatever the appropriate term is)...DD is so slow it would have taken her two hours just to do that subtest.

It is also possible for an eight year old to get 38 correct. And in this case, neither kid may have reached the discontinue criterion (the point where several items are answered incorrectly and the subtest is stopped). However, the impact of this type of ‘ceiling’ (running out of questions) increases as a child gets older. If the extended norms are used, the standard score for the eight year old may increase from a 19 to a 28 (the highest possible standard score using the extended norms), but the standard score for the fourteen year old may only be able to go up to a 20 with the extended norms and may even stay at a 19 on certain subtests. There just aren’t enough questions on the WISC to extend the norms above a 19 after a certain age. So while the IQ scores of both the 8 and 14 year olds would be considered underestimates if the discontinue criterion were not met (both children may have been able to answer more questions had there been more available), you’d expect the underestimate to be much more severe for the fourteen year old.

I think this is one reason Linda Silverman from the Gifted Development Center believes that ages 4 - 9 is the best time to test gifted children (see http://www.gifteddevelopment.com/PDF_files/problems.pdf). The extended norms can be used to differentiate HG, EG, and maybe even PG kids in this age range. But once kids are older, there just aren’t enough questions on the WISC to measure the full range of abilities.

When I looked up the extended norms for her age I think it was 22 giving her a bonus of 3 points. Maybe if a 6 year old had answered all of them correctly, it would be 28.
Hopefully they are making the WISC harder so people aren't hitting ceilings so much. Seems to happen a lot on this site, at least.