Gifted Issues Discussion homepage Forums Identification, Testing & Assessment Min time gap required between the WPPSI and WISC?

I know that there's a 1 year minimum between testing times for each of the WPPSI and the WISC, but does this apply as well to the last time a child took the WPPSI vs. taking the WISC? Context: DS took the WPPSI as a 5yo in Feb 2021, but we want the WISC for a more complete picture now that he's 6 - do we have to wait till Feb 2022 or is it ok to take the WISC already?

Technically, it's better to wait 24 months between administrations. That's the point at which the test-retest effect falls into a range comparable to normal standard error.

There are four subtests in the core that have analogs on the WISC-V (you need one more for the GAI, three more for the FSIQ, and six more for the five factor core indices). Typically, the nonverbal subtests have larger retest effects, so I wouldn't worry too much about two of those overlapping subtests, which are verbal.

I generally wouldn't advise retesting on such a short interval, but from the standpoint of test-retest effects, it's probably not terrible. I would be more concerned about whether your DC is more reliably testable now than he was only 9 months ago, because if you do the WISC now, then you definitely shouldn't be doing it again until he's at least eight, so if he isn't developmentally ready to give optimal performance, you'll just have pushed off a solid retest for another two years, vs, for instance, waiting until next summer to test.

Hi,

A related question I have is how stable are these test scores over time?

I found a recent study

https://www.tandfonline.com/doi/full/10.1080/21622965.2021.1875827

that suggests that WISC-V test and retest FSIQ scores have a 0.86 correlation with an average gap of 2 years for a sample of kids aged 6 to 15 (N=225)

This is helpful, but I am specifically interested in the correlation between adult and child IQ - so if I get a WISC-V score for a six year old, how predictive is it of their aptitude at age 18?

I imagine these studies are hard to do well, but someone must have done something...

Thank you so much aeh!

I did suspect that DS's previous FSIQ on the WPPSI of 129 was an underestimate because it was noted that he was bored and slightly distracted in a couple of the subtests.

We just did the WISC-V 9 months later and it came back at 145! Shockingly his processing speed index went up very significantly. We asked the psychologist to triple check that no mistakes were made and it's true.

How is this possible and should we treat the WISC as a better indicator than the WPPSI?

Oh I should add that the processing index went from 79% to 99.8%! I guess he was super distracted on the WPPSI?!;)

Very nice!

So I should note that all of the same caveats about young examinees are still applicable on this WISC (even though the scores are a bit higher): he's still very young, with the possibility of score instability because of natural variations in testability that affect how applicable the norms are to any individual student. In this case, that translates to the possibility of some regression to the mean in the future. But generally, it does appear that he was more engaged for this administration, and certainly one would hope for increased testability with increasing maturity!

The increase in the PSI especially may reflect differences in attention and even in fine-motor development between the two dates. It's also a different kind of task from a fine-motor standpoint. Typically, I would expect young children to do better on the WPPSi task (stamps) than the WISC tasks (pencil marks), but then again, that's going to be the case across the board (with most kids), so if he has good pencil skills, the WISC comparing him to a range of just-six-year-olds who include kiddos with limited pencil skill advantages him.

He did have a fair amount of intra-Index diversity last time too, so if he simply was more consistently close to the higher of each of his previous scores in each index, the global scores would be expected to go up.

One way or the other, you now have DYS qualifying scores for him!

Thanks aeh, what would we do without you:) Am now scrambling to apply to DYS since the application cycle closes end of Nov

timeout,

This 2011 study by the Thomas B. Fordham Institute may be of interest.
https://fordhaminstitute.org/nation...altitude-performance-trends-top-students

Achievement is a result of both intellect and opportunity.

Excellent point, indigo.

But to the question of predictive correlations specifically for cognitive assessments: yes, those .8ish numbers have been found in other research as well, with other citations in the .7s. If you look at the Scottish Lothian Birth Cohort longitudinal studies, you'll see numbers in the .5 to .6 range (these are in comparison to old age, though).

My response to one of your posts on another thread may be relevant too.