The three core subtests of the verbal comprehension index are normally similarities, vocabulary, and information. Comprehension is a supplementary subtest, usually administered if something seems inconsistent about the other results. I'm not clear on which subtests your daughter was actually administered. The scaled scores for subtests range from 1 to 19, so 19 is the top score, at the 99.9th %ile. Scaled scores of 10 and 11 are average, at the 50th and 63rd %ile, respectively (not statistically different from average). Assuming that the subtests you report as 10 and 11 are vocabulary and information, one of the differences between them and the other two verbal comprehension subtests is that they are more factual in nature, and thus more reflective of instruction and exposure, where similarities and comprehension, while, of course, affected by educational experience, have a closer connection to native verbal thinking ability.
But since you say that your daughter was deliberately answering incorrectly, the difference between the subtest scores is not all that relevant. She could not, however, "fake" the high score, so it suggests that that is a valid measure of her ability in that skill. Perhaps you can clarify which subtest that actually was. Also, it is much harder to fake incorrect responses on the perceptual reasoning portion of the test, which you did not report, as the tasks are less school-like. From the GAI you give, it looks like she scored in the High Average range on that index, which would suggest a genuinely diverse profile.
BTW, is there some reason that she would feel it is necessary to downplay her abilities on this kind of testing? I usually explain to students that everyone does differently on this test, because everyone learns best a different way. The objective of giving the test is primarily for their own benefit. 1) To help her understand herself as a learner. 2) To help teachers understand the best way to instruct her, that is suited to her learning style. 3) Legally mandated reasons that depend on the reason for referral (triennial re-evaluation for students on IEPs, teacher referrals because of educational concerns, parent referrals because of educational or other concerns). With this age of student, in particular, I am very upfront about the purpose and value of testing on an individual and institutional level, and we often have quite a lengthy discussion about this prior to beginning formal testing. And I conclude by explaining that their only responsibility is to do the best they can, so that we get an accurate picture of them and their learning style. If they choose to do otherwise, they will lose a lot of the value of the time that we have invested together in the exercise. I would like to know, in your daughter's case, why she feels she needs to conceal some of her ability from other people, even in a confidential, one-to-one setting with a professional. And, unfortunately, she cannot now be re-tested with the WAIS-IV for another two years, and still have what is considered a valid result, even though this one is probably not valid, either.
