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A Full Scale I.Q. (FSIQ) of 158-160 is different than an a General Ability Index (GAI) of 158-160.

According to Pearson's free online pdf document, "The What, When, and How of the Wechsler General Ability Index": emphasis added

A large discrepancy in scores may indicate a learning disability. A gifted child with a learning disability may be called twice exceptional (2e). If this may apply to your child you may benefit by becoming familiar with wrightslaw and the book From Emotions to Advocacy.

sully, was this score on a WISC IV or another test (I believe the WPPSI may have or also has a GAI)? This may be helpful from the Davidson database:

"What does it mean when a child scores within the gifted range on the Verbal Comprehension and Perceptual Reasoning Indices and shows much lower scores on the Working Memory and Processing Speed Indices of the WISC-IV?

It is common for gifted children to show significantly lower scores on the Processing Speed and Working Memory Indices of the WISC-IV, when compared to their performance on the Verbal Comprehension and Perceptual Reasoning Indices. However, very large discrepancies can sometimes be indicative of problems with attention or something else that is getting in the way of a child being able to focus or process and respond to information quickly (i.e., anxiety, depression, visuomotor coordination, perfectionism). When this is the case, a comprehensive neuropsychological evaluation would be required to help tease this apart.

What is the General Ability Index (GAI) of the WISC-IV?

The General Ability Index (GAI; WISC-IV Technical Report No. 4, 2005) provides an estimate of general cognitive ability that is less sensitive to the influence of working memory and processing speed. This may be used as a substitute for Full Scale IQ to determine eligibility for placement classification. The GAI is often used instead of the Full Scale when assessing gifted children. Because the processing speed index (PSI) and working memory index (WMI) of the WISC-IV are not the best indicators of intellectual ability, many clinicians don’t administer them when assessing for giftedness and it is not uncommon to only report the GAI ."

My understanding is that it is NOT uncommon for a HG+ child to have a higher GAI than FSIQ, and that it is not necessarily indicative of a learning disability.

I will defer to someone more knowledgeable about the rarity of the score, but I believe that most charts I have seen suggest that it is well above the 99.9 percentile.

Here's the link I always share:
http://www.iqcomparisonsite.com/iqtable.aspx

From that you can translate the normal score (158-160.) I'd probably round it to 1 in 25,000 if I wanted reference it.

These are standard scores that represent a position on a curve. To translate to a percent, you only need to know the middle point and the size of a standard deviation. These tend to be 100 and 15 respectively.

So, whether it is an achievement test, an IQ, FSIQ, GAI, a military placement score, or whatnot. With the same mean and standard deviation, it translates to the same percentage. It's part of the appeal of standard scores.

Now whether IQ is in truth a Guassian or Ln-Normal or other distribtuion is another topic.

Here is everything you ever wanted to know but were afraid to ask about the GAI and the WISC-IV. All it says is ">99.9" starting at 150. However, it does have a discussion about discrepancies between the GAI and FSIQ.

ETA from that booklet:

Just a small point for OP - are you talking about a GAI calculated from extended norms? It's probably not material to your question since either way it's >99.9. But if you were somehow trying to get more granularity on that (i.e., is it >99.9 or 99.99 or 99.999, etc.), the distinction might be important.

Or not. I'm really ignorant here. But I do see the note re "extended norms" systematically attached to our DS's scores and discussions about them.

Currently, 158-160 is interpreted as meaning 99.99 %ile, or one in 10,000. Above comments on the questionable gaussian distribution of IQ do apply, but we have little hard data on this, due to rather small available population for study.

Another factor is that it's a bit easier to get a high score if you pick your best score out of FSIQ, GAI, VCI, PRI, etc.

Fwiw, I didn't understand how this was a factor either. Could you explain?

If you're going to report the highest number achieved out of FSIQ, GAI, VCI, and PRI (those are the Davidson criteria, I think), then you have a greater chance of one of them being over a certain threshold than the chance that just the GAI will be over a certain threshold. It is also complicated by the fact that not everyone gets a GAI calculation - it is properly only added to a test report if there is a significant discrepancy in subscores, which probably means that the reported GAIs skew high. So there are probably more people entitled to run around saying, "I got 160 on my IQ test"* than you would think just on a straight normal-curve calculation.

* This should not be taken as an endorsement of bragging on IQ scores for yourself or anyone else socially.

It is good for parents to know how rare their child's intellectual profile may be, especially toward understanding that the teacher may not have seen a student of similar caliber. That said, some schools perform their own testing and may not accept outside testing, such as private test scores and results.

There is quite a bit of advocacy information and meeting prep information on the forum, much of it sourced from articles on the Davidson Database and resources listed there.

Here's a thread on advocacy with many resources mentioned.

Tips for meeting prep have been posted on other threads but in case it is helpful, here is a brief summary:

- Research state laws and the school or district policies and practices. This information is often found online. You may wish to print and put this in an advocacy ring binder to refer to over the years as the laws and policies/practices may change over time.
- Have any test results and other pertinent facts available to share (milestones, reading lists, other accomplishments/achievements)
- It is good to have them speak first. If asked to speak first, you may simply wish to thank everyone for attending and summarize that you are all here to share information and ideas about how to best meet your child's educational needs... and that you would like to hear from them.
- Agenda
- Know who is in the meeting, and their role(s)
- Stay calm
- Know what you are asking for
- TAKE NOTES including Who-What-Where-When-Why-How of support services and/or differentiation, so you can summarize in an e-mail afterward [Some families announce they plan to record the meeting and then do so, rather than taking notes.]
- Use active listening (rephrase what has been said, and put it in a question form) to clarify understanding
- Be open to receiving the school's data/observations.
- Listen to any proposals they may make, ask appropriate probing questions, such as how a proposal may work, how the proposal may help your child, the schedule/frequency of service delivery, etc
- Do not be forced to make a decision if you need time
- Summarize next steps & time frames, and/or need for a follow-up meeting
- Thank everyone for their time & interest
- After the meeting, write a summary (points of agreement, etc) and share it, possibly by e-mail

To put it into perspective, in the US about 400 graduating high school students a year will have a GAI that high or higher. Of course, there will also be about 400 who have FSIQ that high or higher, who are a few points lower, but harder working, etc, etc. But that gives you an idea of the numbers involved.

It's not an exact science so far from the mean, but that's a score so high that it's unlikely your child's school has ever had a similar child. Seriously. There's as much difference between your child and those who qualify for the gifted program as there is between them and the average student. IIRC, 130 IQ is about 1 in 44, and more common in higher SES/ highly educated places. For example the district I just googled has a threshold of 95% on the OLSAT, and 10% of their students qualify.

Personally, I'd join Davidson.to get help with the advocacy.
A couple of people asked how this is relevant. All the scores are calculated independently, not all kids have a FSIQ as far from the mean as their GAI. You could have a 50+ point spread between the lowest and highest of the scores. The set of people with PCI over 145 overlaps but is not the same as the set of people with 145+ IQ or the set of people with 145+ GAI, etc. 22B is trying to reassure you. It's not quite as dire a situation as the rarity of that one score suggests.

Aeh can probably explain it better and more correctly, but this is my understanding.

In an ideal world, yes. In reality it means that your kid is insanely, crazily, impossibly smart, but no teachers will see him that way because he's not fast. I'm sorry, but it's going to make both advocacy and accommodating him orders of magnitude more difficult.

I'm not trying to be mean, but I am trying to be realistic. I have a child like this, I have friends with children like this and it's incredibly difficult to find the right teaching fit for them. People see speed. If they don't see speed, they will discount every test under the sun. No matter what evidence you have, they'll stick to the fact that he's not the first person to finish his math problems, and for them that will prove that he's far from being the smartest kid in the class. This is how humans work. They'll think you're a crazy hothousing delusional obsessive. I strongly urge you to apply for Davidson to get help with this.

More common but still unusual

FWIW, my understanding is that when there is a greater than 1.5 SD difference between subtest scores, the FSIQ is not valid, so I wouldn't use it to describe my child's abilities. I have a 2e kid with a large spread between subtest scores - so we use the GAI when we are trying to frame his intellectual strengths. That's not saying we ignore the other subtest scores, but his lower FSIQ score is more of an average that lies somewhere between the high GAI and the lower processing speed/wm… hence it's more like a meaningless number - it doesn't tell you much of anything at all about ds, other than what would happen perhaps if you averaged a numerical representation of his strengths and not-quite-as-strong abilities.

I suppose that some would then counter with - well, isn't that what FSIQ is for everybody, but from my understanding, most people do not have those huge discrepancies in between FSIQ subtest scores, so averaging subtests for the typical person is valid.

And I realize I used "averaging" in a broad sense here, because FSIQ isn't a straight average, I think it's weighted a bit between subtests.

polarbear

Another point to consider, what is the subset within that 400 that have the same specific combination of strengths that your child has? Or with the same magnitude of discrepancy when looking at PSI/WM?

polarbear

Don't know if it's of help but have you seen the following. There is a chart there that gives some idea how to interpret the GAI.

http://images.pearsonclinical.com/images/assets/WISC-IV/80720_WISCIV_Hr_r4.pdf

Just think of a Venn diagram.

sully, I am sending you a PM.

and Agreed. This may skew high. Some may say this entails a bit of cherry-picking through the child's scores to present the highest scores, which may not be the most representative. I'm linking to a related post, How much error can there be in test scores?

While some may prefer the GAI as they believe it to be more descriptive of a child's intellectual ability, a child's Working Memory and Processing Speed (whose scores are more apparent in the FSIQ) may greatly impact the child's daily classroom performance and achievement.

Linking to an old thread, FSIQ vs GAI.