Quick question on WISC/WAIS interpretation

[LucidMind]

Hi guys and gals,

i'll try to make this short. As i'm sure most of you are aware, if the WISC or WAIS four Indexes do not have a difference that is 23 or greater the FSIQ is interpretable.

The next step is interpreting whether each of the 4 indexes are unitary or not, which determines how interpretable those are.

I'm confused as to why you can interpret the FSIQ, even if one or more of the 4 indexes are not unitary? As long as the indexes themselves are not 23 points or greater different, it's fine. But if the indexes are not unitary, you can't interpret them specifically but still the FSIQ?

Man....I hope my question isn't too convoluted lol. That's why I don't want to ask a professor, i'll sound like a whacko. Thanks for your help!!

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[Rivi]

This isn't a whacko question at all. It isn't so much that the FSIQ is interpretable/uninterpretable. The FSIQ is always interpretable (assuming the test was completed appropriately, etc.), it's just not as good of a descriptor of a person's intellectual functioning in the cases with significant variability (i.e. PRI=120, VCI=80). Most reports still list the FSIQ, regardless of how much variability existed amongst subtests, and acknowledge the limitations of the FSIQ in these cases. Regardless, you are correct to question the broad nature of the FSIQ. A FSIQ of 100 can consist of many different combinations of subtests. It is when these differences between the subtests are significantly different that we should be more cautious to tack a broad label on someone's intelligence (and I think we should always be reluctant to tack a broad label on someone's intelligence).

Edit: I hope this makes sense

 

[LucidMind]

That does make sense! Thanks for the reply Rivi!

 

[G Costanza]

I do not list the FSIQ in my reports if the variability between indexes is too great. But I also explain why I don't list it.

To the OP- I've wondered that myself and as far as I know, the manual nor any text I've read addresses it.

 

[WalksAsOne]

I do not list the FSIQ in my reports if the variability between indexes is too great. But I also explain why I don't list it.

To the OP- I've wondered that myself and as far as I know, the manual nor any text I've read addresses it.

I can't find any compelling support for the notion that variability among index scores renders an FSIQ uninterpretable. My understanding is that that is an outdated practice. See this article for an analysis of this issue: http://edpsychassociates.com/Papers/FSIQvariability(2007).pdf.

 

[Therapist4Chnge]

I always include the FSIQ (with the exception of an invalid profile) because many providers ask about it. However, I always explain that the score means within the context of normative data as well as what it means to the individual case. As an aside, I don't really like index scoring as a construct (too much of a 'data in a blender'), as I'd prefer to look at things from the sub-test level and tease out more specific things across measures. I always have my psychometricians put together a computer scoring summary for reference, but often that is just more data…not necessarily the most useful data to me.