Gifted Issues Discussion homepage Forums Identification, Testing & Assessment KBIT correlation to WISC

This is my first time here! I am the mother of a bright 7 (almost 8) year old girl. B has always been advanced for her age, but as a teacher myself, I still sometimes questioned whether she was bright or gifted. Well, after moving into a new school district, I finally asked for her to be screened for gifted. I just wanted to see if she was gifted - and if so - wanted her to start getting the instruction that she needed. The school gave her the KBIT and her results were as follows:
Verbal 129 (97th percentile)
Nonverbal 143 (99th)
Composite 141 (99.7th)

The counselor was surprised by the results, saying that B took a very long time to think through some of the questions,but was the highest student she had tested and that it was important to get her the instruction she needs. However, it is late in the school year and she may not get the WISC completed until the beginning of next year. I understand this, but my question is about the WISC. What is the correlation between the scores on the KBIT and the WISC? I can't find much out there about this. I want to know if it is timed or if B will be allowed to take as much time as needed. She is very meticulous about her work. Is it possible she could score a lot lower on the actual evaluation and not qualify? I know she needs to score at least a 130 on the WISC to qualify for the program, and with a 141 on the KBIT she seems like she will be fine. Or is there a discrepancy between the two tests?
I hope this all makes sense. If you have any thoughts, please share! Thank you!

Welcome!

I cannot speak to any possible correlation between the KBIT and WISC, but will point you to this link at Hoagies' Gifted Education Page, to show that there is a wide variation in IQ scores from different test instruments. Hoagies' page on Why do my child's test scores vary from test to test? is also a good read.

This list of common gifted acronyms may be of interest. For example, going forward, your daughter might be referred to as DD7 or DD8.

I haven't seen the data on KBIT-2 to WISC-V correlation, but historically, correlations have been about .76 or .77 for the WISC family and the KBIT-2. With regression to the mean, that would predict a WISC-V full scale in the 130 range. I would not worry too much about qualifying scores.

The WISC-V does have timed measures and untimed measures. Many GT assessments downplay the memory and speed aspects of the test (they can't be completely eliminated) by calculating a GAI, which doesn't include specific measures of speed and working memory, instead of an FSIQ, which includes them.

I have been reading the information on Hoagies' page and it is helpful. I guess I'm just wondering why there are so many variations in IQ scores from different assessments.

There are two primary reasons why cognitive assessment measures differ, both statistical in nature:

1. Standard error/regression to the mean
2. Differences in how they attempt to quantify underlying constructs.

1. There is natural variation in the way individuals perform on tasks from occasion to occasion, which means that any individual measure is only the best estimate of some hypothetical "true" value for that task. If we could guarantee ideal performance on any occasion, then we might be able to claim a true measurement. We can't, of course, for a host of reasons, including how much sleep the student had the night before, whether the examiner made a judgement call on scoring a marginal response, the level of engagement the student had with the examiner and the task, whether seeing "0"s and "1"s encouraged or discouraged the student, etc. So scores are supposed to be reported in confidence intervals (ranges), to capture the idea that this is not a hard-wired number, but a best estimate.

In addition, regression to the mean says that, because scores far away from the mean are relatively rare, it is even more rare that two scores that far from the mean will be obtained. Practically speaking, this means that, if you administer two tests that purport to measure the same thing, and the first one is quite far off the mean (say, very high), the expectation is that the second measure will be closer to the mean (i.e., lower, in the case of high GT-type scores).

2. Each assessment is attempting to sample skills related to an underlying construct (in the case of cognition, this is usually "g", or general intelligence--those researchers of cognition have had an ongoing discussion on this for decades). But each test developer selects different exact tasks and items for this, each of which may sample g to different extents (unless you believe that g is really a whole host of subscripted "g"s, in which case maybe you are sampling different aspects of cognition altogether; or perhaps some combination of the two).

The bottom line is that measurement error and differences in sampling embedded in the test designs mean that cognitive assessment scores are quite commonly different from administration to administration, and from test to test. And if you test enough times, you will probably come up with a few outliers (notably higher or lower than the hypothetical "true" score) eventually.

Thank you for summarizing it all nicely. I just don't have the time to research everything.
So, the fact that my D7 performed very well on the KBIT leads me to believe that her performance on the WISC could be poor or could come out higher. I just don't want to make her go through the entire process for the evaluation if there's a chance she won't score at or above 130. She is usually pretty consistent and will hopefully perform well when she is evaluated.

This old post has links to two articles on IQ test prep - one by Aimee Yermish, one by Nadia Webb. In a nutshell child should be:
- well-rested,
- well-fed (healthy foods),
- cautioned not to give silly answers even if some of the questions seem silly, too easy, or have ridiculously obvious answers.

Great to know! Thanks!!