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DS took the CAT last week. I just checked his results online and am confused. He didn't miss a single question on any part of the test, Yet his NPR (national percentage rank) ranges from 90 to 98 on different sections, putting him in the 8 stanine for some sections and 9 for others. Can someone explain how this works if he didn't miss any questions?

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All it means that the portion of students who also missed no question varies from section to section.

If he is in the 90th percentile in section A with a perfect score, that means that the top 10% of all kids also had a perfect score in section A.

If he is in th 98th percentile in section B with a perfect score, it means that only the top 2% of students mannaged a perfect score in section B.

Clearly it means that a test like this is not designed to show differences in performance among the top students.

ETA: If you had a test where your student scored in the 50th percentile with a perfect score, that would not mean that the student performed poorly, but that the test was so easy that half the kids got everything correct.

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That means that a lot of kids didn't miss any questions. Especially on the 90% section. Basically, on that test, 10% of the kids score a perfect score on that section. On the 98% section, 2% score a perfect score. The scores are based on how well he did compared to a normed group of students. The percentile is not a percent of how many he got correct. Stanine scores just break it into a single digit score. 7,8,9 are above average. Since so many students did well on the one area, that area's top stanine would be 8. A 9 stanine would usually indicate being in the top 4%, but if 10% of students all scored a perfect score, the best you could do would be an 8 stanine (actually, I think that should be a 7, but whatever).

I assume this was the survey CAT? With so few questions on the test, it is not a great test for breaking down statistically. It does let you know your student is doing just fine. A full battery test is more reliable and gives more accurate information.

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Okay, thank you!

We weren't testing to find out anything, just for the experience of a standardized test so he'd understand what's expected during them (asking questions during appropriate times, not talking, stopping when told, waiting, filling in bubbles, etc.). So, I really didn't care at all what the scores were (which is why we went with CAT since it was cheapest), I was just confused about it. I get it now, thank you!

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In first grade Melody got an 82nd percentile with a perfect score on one section. I laughed and said clearly that test was too easy!

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Different tests have different ceilings, especially in the lower grades. There was one subtest on the 1st grade SAT-10 where a perfect score was only something like the 60%-which lowered my DD's overall % rank on that section overall.

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This is the reason why I don't like the CAT. I usually give it for the same reason as the op, to get my early elementary kids used to testing.

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