Gifted Issues Discussion homepage Forums Identification, Testing & Assessment Rarity of GAI vs. FSIQ and extended norms?

I'm still processing DS7's scores from a couple of weeks ago and am now to the point where I'm thinking "But, it doesn't really mean *that* rare, right?". So, his GAI is 153 and FSIQ is 139. The FSIQ seems nice and manageable, nothing too scary. But the GAI seems less straightforward.

Does a high GAI have the same rarity as the equivalent FSIQ would? On the GAI tables, the average is still 100 but, with less input to affect the score, wouldn't it mean it's easier to get a higher GAI?

Also, how do the extended norms fit in? Does the 145+ mean "beyond measure" with the GAI, even though there are extended norms that measure much higher? If it's possible to score higher, then wouldn't it mean that the test is more sensitive at the upper tail and a score closer to the old ceiling of 160 is much less impressive since the test can go to 210, thus discerning between true 145s and those that were subject to ceiling issues?

Finally a bonus question, lol- I read somewhere that scores between 17 and 19 represent ceiling scores. Was that only true before the extended norms? The tester specifically said that DS7 didn't ceiling any tests and his 18s were true 18s, not subject to the extended norms. How can a 17 or 18 be a ceiling if there were still more questions that could have been answered?

I hope something in there makes sense! Maybe I'm just over thinking this whole thing and it's much less confusing than I'm making it.

Thanks!

Having just emerged from the ocean of testing...I would suggest that reading through both WISC tech reports #4 and #7 would prove helpful to you.

It seems to me that GAI (and even extended scoring) is most helpful when you suspect the child has a learning challenge. FSIQ is supposed to be a composite score of four different categories. Together, that score is useful in determining strengths and weaknesses. My sons' strength (VCI -152) balanced out his weaknesses (PSI-126) to give me a composite number that matched up quite well with his achievement test scores.

Here is a quote from the WISC tech #4 that I found helpful during the testing process:

"It is important for practitioners to recognize that the GAI is not necessarily a more valid estimate of overall cognitive ability than the FSIQ. Working memory and processing speed are vital to the comprehensive evaluation of cognitive ability, and
excluding these abilities from the evaluation can be misleading. The classroom performance of two children with the same GAI score but very different WMI/PSI scores will likely be quite different. In educational situations where evidence of a
significant AAD is required to obtain services, the GAI may be used as the ability score; however, the WMI and PSI should still be reported and interpreted.'

HTH
-cc

My understanding is that it is normed so that the average is still 100 and the standard deviation is still 15. A GAI of 153 is in the middle of the 3rd standard deviation (145-160). A 146 on FSIQ or GAI is, theoretically, at the 1 in 1000 level. A 160 is, theoretically, at something like 1 in 10,000.

Because not many people score at these levels, there isn't a whole lot of data to back of the "theoretical" part, and I gather that pinning down the rarity of these scores is hard to do.

Also, keep in mind that the "map is not the territory". The scores are normed to reflect the rarity of the scores themselves. Just what it is that the scores are measuring is another matter.

Personally, I'm just beginning to come out of my own research/obsession with the meaning of my DS's scores. It seems to me that Dottie has a very sane take on it all :-)


I'm not sure what you mean. Did your son's report actually include a score cited as "145+". The percentile associated with a score over 145 always seems to be "99.9+", but I don't know what 145+ would mean.


I think that scores in the 140s are impressive regardless. Before the extended norms, however, you just knew it meant "off the chart". The extended norms give you an idea how far off the chart.


I suspect this means that more than 18 questions were asked, but that only 18 were answered correctly. I gather that after you get a certain number wrong, the tester stops asking. So if your DS got 18 of the first 20 questions right, and then missed 3 or 4 in a row, the tester would have stopped there after question 24. (But I'm quite fuzzy on this aspect of testing, so I could have this wrong)

If you DS had gotten 21 questions right, that score would still have been reported as an 18 for the purposes of computing FSIQ and GAI. If there were two tests on which he exceeded the ceiling, then the tester would computeand report an "Extended FSIQ" and "Extended GAI" in addition to the regular FSIQ and GAI that you got.



I think I know what you're going through. We're now 6 weeks post-testing and I think I've mostly gotten past my need to understand the numbers. Hope this helps!