Gifted Issues Discussion homepage Forums Identification, Testing & Assessment Younger sibling's results

We tested younger DD at 3 yr 9 months. Her results came back at substantially lower than older DD (who was tested at 3 yr 11 months). The difference is an astounding 18 points lower (high average) and 22 percentile points lower. Needless to say I am a bit shocked. We expected younger DD to test lower, but not that much lower.

Results:
(results removed)

When discussing the results with the psych, we both did not expect verbal to be so low given how much of a chatterbox younger DD is. However, the psych remarked that her vocab didn't show the higher order level required for a higher score. We are a dual-language home, so I am not that concerned and hope there is room for improvement. Also younger DD is at home with the nanny whereas older DD had more formal schooling by this age. She will be going to full time school in September.

Working memory was also lower than expected. The psych remarked that younger DD remembered locations, but would mix up the animals.

Visual spatial is the strongest, but I thought she would do better.

On the Kauffman Test of Educational Achievement, younger DD scored about a year ahead of her age.

I am hoping younger DD can attend the same gifted private school as older DD. I am a bit disappointed. The older DD is a textbook child, the younger DD, not so much. I am hoping she's just slower to blossom. She never crawled and went straight to walking. Took a long time to learn to speak, but once she was speaking it was in almost full sentences.

Can anyone offer any insights into her scores, the discrepencies with older DD, and tips on how I can work with her to improve her scores before retesting next year?

Because you mention the difference in early environment between these two children (formal schooling vs nanny), here's a link to a recent post on enriched home learning environments which may be of interest.

Is there a reason why you tested her so early? I really don't think these tests are very reliable at such young age and you shouldn't make any education decisions based on them.

The primary consideration is her age. Scores at this age are notoriously unstable, and really shouldn't be considered more than a ballpark measure of current performance, rather than predictive of her long-term development or outcomes.

As to working with her to improve her scores? I would not do anything that you wouldn't naturally do as part of raising a happy, healthy, curious preschooler. Prepping for cognitive assessments is not recommended. Nor should she, actually, be tested quite so frequently. Typically, the recommended interval for valid results is 24 months between administrations of the same test. Although she will be eligible for the upper level of the WPPSI-IV next year, there will still be some overlap in subtests, which may result in an inaccurate picture of her. (Also, even a year from now, she will be very young, so all of the same caveats about unstable scores in small children still apply.)

The best things you can do with her to aid her development are the things you would do anyway as a loving parent--share a variety of interesting experiences with her, follow her lead in pursuing her own creative interests, listen attentively and converse with her, spend time with her, etc.

We decided to test early as older DD was tested at this age, so we figured why not. We need to test her for purposes of School admission.

I guess I'm a little shocked and concerned that my baby may not get into my older one's school. I actually think she's very bright, might even be brighter than the older one, but she presented differently than the older one who's more textbook.

While I doubt the test is reliable there is a 15 point gap between my kids. I think a lot of it is personality but that doesn't change the scores. All you should do is check the nanny has the resources and skill required. I assume when you say she will be in full time school come September you don't mean academic stuff.

I’m curious as to why you “thought she would do better” and why you consider 2 different children having different scores to be a ‘discrepancy’. Kids aren’t made from cookie cutters. I have degrees from top 20 schools/800 standardized tests. Neither of my siblings went to college. My 2 kids are about 15 points apart - I work with both to maximize their potential. Human’s vary. Maybe it’s just me, but you questions sound like you’re asking how to ‘fix’ her.

The standard deviation of the difference of IQs of two children of the same biological parents is about 15, so a difference of 18 points is not too unusual.

Here is the math. If x1 and x2 are drawn from a distribution with standard deviation s, and common mean, and have correlation p, the standard deviation of (x1-x2) is s*sqrt(2*(1-p)), where p is the correlation of x1 and x2. This is because

variance(x1-x2) = <(x1-x2)^2> - ^2 = + - 2* = 2*(1-p)*s^2

The Heritability of IQ article of Wikipedia says p is about 0.5 for siblings, and plugging p=0.5 into s*sqrt(2*(1-p)) gives s, which is about 15 for IQ tests.

Yes, and with regression to the mean you would have to expect the deltas for siblings to get even bigger the further one of them is from the mean.

Since you mentioned being a dual language family, are there ways the verbal environment is different for your second child, ie did the language family members use shift away from the testing language? Which language are the kids using among themselves during play? Which language with the nanny? was the older kids formal schooling in the testing language? All of these can make a difference.

Yes,yes and yes. I didn't realize it would make that much of a difference, but reflecting on the differences, it makes sense. The nanny speaks English as a second language. The older child was in school for more time.