Putting Percentiles into Perspective
After testing has been completed, parents receive a lot of test scores, grade equivalents and percentiles. It’s a lot to take in, and takes some learning as to what they mean. Percentiles can be confusing and somewhat deceptive. Parents often ask questions like “How can the 27th percentile mean Average?” I want to use an analogy to look at percentiles with a more realistic perspective. *Remember this is an analagy and does not take into account the various factors that occur in real life.
Let’s use IQ scores as an example. The entire third grade was given an IQ test, all 100 children. They were then numbered by their score. Number 99, 98, and 97 are highly gifted. Number 1, 2, and 3 have subaverage intelligence. The majority of the third grade fell in the Average range (numbers 25-75) and theoretically “should” be able to learn with Average instruction. Number 75 will have an easier time than 25, but they are both in the average range. Numbers 76-96 are not technically “gifted” but they learn faster than average and school should come pretty easy for them. Numbers 4-24 are below Average and will need accommodations or more repitition to learn. Number 4 will have an extremely difficult time, while number 24 may need just a bit more repitition.
This analagy can be used on any assessment. If we use Math scores on achievement testing and numbered 100 kids according to their performance on the math test, a few would perform way above grade level, a few will perform way below, but most will perform right at about grade level.
The assessments used in special education testing were given to thousands of children to help standardize the test and give percentile ranks. When your child took the test, her performance was compared to all the other children given the assessment in the standardization and a percentile score was given. All other scores (Standard Scores, T Scores, and Scaled Scores) are formulated based on the percentile.
Be aware that the percentiles are theoretical. Scoring at the 75th percentile does not gaurantee good grades. Often number 50 on the IQ test will be around number 50 on a math test and a reading test and so on. Unfortunately, people expect that to always be the case. There are a variety of factors that can make a child not perform at thier potential (i.e. processing disorder, attention problems, emotional problems, etc.) – but we’ll save that for another time.
I also reccomend www.assessmentpsychology.com for more good information on test scores.