WAIS III vs WAIS IV

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WAIS III vs WAIS IV

Postby nearlythere » Thu May 24, 2012 9:20 pm

Hi all,

I'm a recently qualified clinical psychologist who has been lurking on the site for a while now! I've been thinking about a dilemma (I think) of sorts that I would be interested in obtaining other's views on.

The service I work in (CMHT) uses the WAIS III rather than the WAIS IV and recently a colleague referred someone to the LD team on the basis of an assessment. I've begun to wonder how valid the 'older' version of the WAIS is and wondered if I could some of your views on this? I don't want to raise it as an issue if it's perhaps me being too precious over it. My colleague who was aiming to be (and always is) very helpful reports that apparently the WAIS III is used a lot in private practice as people don't want to buy a new upgrade!

I'd appreciate your thoughts on this and any direction on guidance out there
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Re: WAIS III vs Vs, WAIS IV

Postby Borrowed Cone » Thu May 24, 2012 9:38 pm

nearlythere wrote:Hi all,

I'm a recently qualified clinical psychologist who has been lurking on the site for a while now! I've been thinking about a dilemma (I think) of sorts that I would be interested in obtaining other's views on.

The service I work in (CMHT) uses the WAIS III rather than the WAIS IV and recently a colleague referred someone to the LD team on the basis of an assessment. I've begun to wonder how valid the 'older' version of the WAIS is and wondered if I could some of your views on this? I don't want to raise it as an issue if it's perhaps me being too precious over it. My colleague who was aiming to be (and always is) very helpful reports that apparently the WAIS III is used a lot in private practice as people don't want to buy a new upgrade!

I'd appreciate your thoughts on this and any direction on guidance out there


Hi nearlythere!

Ol' David Wechsler would have us believe that only the newest version is valid, given the advances in research and understanding of "intellectual function". Does this mean the the old version is invalid in someway? I personally don't think it does. I think it is perhaps less valid, but I don't believe that it offers nothing useful just because a new test has been brought out.

With squeezes on budgets, departments are struggling to upgrade their WAIS-IIIs to WAIS-IVs, even now. Ideally, you'd want a WAIS-IV, and I think it would be useful to bring up that it is not really acceptable to be using outdated tools and push for upgrades; but I don't think it will do any harm to use the III if that's all the department has, for now.

There are some journal articles on the difference between WAIS-III and IV, but I don't have them to hand I'm afraid.

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Re: WAIS III vs Vs, WAIS IV

Postby katz » Thu May 24, 2012 11:12 pm

I think just to reiterate what cone has said, best practice would suggest the most recent tool should be used.

Re validity. The test and it's norms we're validated at point of publication, this means that we are only able to draw conclusions with reference to this specific data. One of the issues is the Flynn effect and adjusting for expected increase in IQ with the passing of time which clearly is accounted for as a new test is developed.

My other concern (less so for a lD assessment but more relevant If assessing for decline) is the ability to compare results to future assessments likely to be conducted with the IV, it can be done but is much more clinically useful if you can compare like for like.

There are other specific differences between the two tests but the Pearson website has a good presentation on these if you want to know the specifics.
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Re: WAIS III vs Vs, WAIS IV

Postby Nephthys » Fri May 25, 2012 5:01 am

Surely if you're assessing decline and you established a baseline with a WAIS III, you'd use the same again regardless of whether you had a shiny new WAIS IV available, for just the reason you mentioned?
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Re: WAIS III vs Vs, WAIS IV

Postby Mexie » Fri May 25, 2012 8:24 am

There is also an argument that we should wait until the new test is firmly established in the research evidence base with papers describing typical profiles in different conditions etc. I don't particularly agree with this, though it's possibly more relevant to medico-legal expert witness-type work.
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Re: WAIS III vs Vs, WAIS IV

Postby katz » Fri May 25, 2012 9:29 am

Nephtys, Your right ideally this is exactly what you would do. This comment came from my experience of service users moving between services (as a side note my experience is not in LD) where often the repeated WAIS will be with the latest version making comparisons more difficult.

Of course, with any assessment the most important thing to consider in an assessment is the ability for the tool and it's norms to allow you to measure what you are looking to measure. In that respect I agree that where insufficient norms are available to make an assessment using the IV in an LD population then it seems to me common sense to use the III.

Again though (i am no expert and I'm not rue of the evidence or this in LD) i think you run the risk of not adequately comparing the service users performance to the expected performance for age and education at this point in time. Tests are made more difficult to account for expected increase in IQ with time. I would assume therefore that you could potentially overestimate an individuals level of functioning when comparing to old norms.

I guess there is no easy answer and it seems to be a best fit judgement.
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Re: WAIS III vs Vs, WAIS IV

Postby eponymous85 » Fri May 25, 2012 9:41 am

This raises a really interesting point re: validity over time. Should someone be reassessed every time a new version comes out, to ensure the results are still valid? Sorry for the flippant example but it does make me think about how rigid we can be with these assessments. I've seen some of the other Wechsler assessment tools still have comparison norms for WAIS III and WAIS IV so there is some scope for extending the length of time a test can be used. Also I haven't looked in to this in great detail, but I would assume that there would probably only be a few points difference between versions, which may make a difference to things like VCI-PRI discrepancy/FSIQ interpretability but if the results are interpreted clinically, do those few extra points make a really significant difference? Perhaps this is my naivety, I know some entitlements to services are very strict with IQ cut offs.
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Re: WAIS III vs Vs, WAIS IV

Postby eponymous85 » Fri May 25, 2012 9:42 am

Hmmm perhaps to be clear I should say I believe in principle that it is good to update the tools and norms over time, but not to stick rigidly to new versions as soon as they come out. After all, the companies that produce them do have a strong vested interest in selling new products!
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Re: WAIS III vs Vs, WAIS IV

Postby jamesivens » Fri May 25, 2012 12:55 pm

The WAIS-IV has embedded tests of effort, which is useful. The 'flynn effect' would also suggest that people taking the WAIS-III today are likely to score higher than the norms group it was originally based on.

The Essentials of WAIS-IV Assessment book has a chapter on WAIS-IV use and interpretation with learning disabilities which may be of interest for further info.
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Re: WAIS III vs Vs, WAIS IV

Postby miriam » Fri May 25, 2012 1:53 pm

In my private work I moved from the WAIS III to the WAIS IV two years ago. However I did use the WAIS-R for a long time when the WAIS III was out to avoid borrowing tests, as I didn't want to buy a new WAIS until the WAIS IV was out (especially as at the time I worked in CAMHS and only saw parents for about one court assessment a month). I figure provided you acknowledge which test you used in your report, and the potential for the population scores to have risen slightly compared to the norms if it is a long time since the test was validated, then the test is still giving loads of useful information.

They also need replacing every 5-10 years simply due to dilapidation, so sometimes the new edition is a welcome excuse for that. I've used lots of test where the materials get damaged, or the briefcase comes apart, or components get lost, and I can't imagine the medics using a similarly worn out stethoscope or blood pressure monitor.

Of course the ideal is to keep up to date, and when I set up my private company the right IQ tests were definitely there on my essential kit list (and I'd argue they are as important to services as many other supplies). I've now got almost the full compliment (WAIS, WASI, WISC, WPPSI, WIAT) but they are pretty expensive, especially under current financial pressures and for people in private practise and smaller social enterprises.
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Re: WAIS III vs Vs, WAIS IV

Postby nearlythere » Sat Jun 09, 2012 3:08 pm

Hi all

I wanted to thank you for the replies and apologise for the delay in responding. I found your comments really helpful and I've shared some of these discussions with my colleagues in work. My manager is still quite fixed on the idea that the WAIS III is fine.

I also spoke with some colleagues in private practice who indicated similar thoughts discussed here. It seems that some people actually 'rent' the WAIS-IV to do private work?! I've never considered this in the small amounts of independent work I do but I suppose it's worth thinking about.

Thanks again
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