Can anyone explain how a percentile rank of 27% is avarage?
The test is WIAT-II
Subtest on Pseudoword Decoding
Score 91
%-27%
Description:average
How can 27% ever be average on a bell curve? Is this a dumb question?
All other % ranks are in the high 70 to high 80’s .
Please help quick meeting next week Thanks shari
You are thinking of % in the same way you think of getting a 27 out of a hundred on a test- percentile ranks on standardized tests do not work that way. On a test- like a spelling test say- a 27 stinks because it means you have only demonstrated knowledge on 27% on the content. On a normed test, percentile ranks describe your standing within the norming population relative to that task. Here is the clinical definition- lifted from the test manual that comes closest to speaking English that I have:)-
Percentile Rank describes performance on a scale from 1-99 relative to the performance of some segment of the norming sample that is at the subjects specificage or agrade level. The subjects percentile rank indicates the percentage of subjects within the normaing sample who has raw scores (number of correct items) the same or lower than the subjects raw score. Percentile ranks are useful (like standard scores) in describing a subject’s relative standing in the population.
Standard scores of 90-110 are generally considered average range, as are percentile ranks of 25-75. Standard scores of 111-120 are high average usually- as are % ranks of 76-91. Hope this helps a bit- you will likely get some other references to check from other folks.
Robin