Gifted Issues Discussion homepage Forums Identification, Testing & Assessment SCAT percentages and extrapolation to general pop

When trying to explain SCAT scores - would it be fair to extrapolate from the test that a child who scored in the 90% percentile on the test (this is just an example) would have score in approximately the 99.5% if the test was given to the general population. I am figuring this by the fact that the test is allegedly given only to top 5% of children on other standardized tests - so:

If 1000 children take a regular standardized test, 50 of them would qualify to take SCAT. A child who scored in the 90th percentile on SCAT would thus be one of 5 of 1000 = 99.5th percentile?

My strength is def. not math or statistics, and I know there are all sorts of other variables - I am just trying to figure out a way to give some sense of where the score would land a kid among the general population.

Thanks, Cat

In theory, that makes sense, but I would bet that there are kids who take the SCAT who are not actually at the 95th percentile. First, not every kid who takes the test has taken a standardized test (parent nominations are allowed, etc...). I can't recall, but if the qualifications ask for 95th percentile, does the child need to have their total composite in the 95th percentile, or do they just need one score over the 95th percentile? If it's the latter, then you are definitely going to have more than the top 5% of kids taking the test.

As a side point, I'm not sure how much I trust the percentiles compared to the norm sample (i.e. the percentiles that they give you, which compare your child to kids 2-3 grade levels above). But I'm assuming that you're talking about the child's percentile compared to the other talent search participants of the SAME grade level.

Thanks much. I know it isn't a great method or test, but I was trying to explain to a person (related to the school but not a bona fide decision maker) who was kind of like, well, 97th and 88th percentile is good but not that astounding, and I was trying to get them to understand that it isn't 97th percentile overall, but 97th percentile of an already fairly select cohort. Not sure if the math was just too much for them or ???

So this does help. Cat

My understanding is that the percentiles shown on the SCAT score report are for normal children of a higher grade. For example, my 2nd grader took the SCAT, and they reported his scores as percentiles for 4th graders.

You're right, Bostonian. Although you can also figure out the percentiles within the talent search pool from the information in the Interpretation Guide. They don't actually give you the percentiles, but you can use the mean and standard deviation info, or crunch the numbers from the bar graphs. (Keeping in mind that this isn't exact as the data is from the previous year.)