Conversion of Percentile to IQ score
By Inderbir Kaur Sandhu, Ph.D
Q: When I was a child, I took the Slosson IQ test and no longer have my scores; however, I was just now told that I scored at least at the 95th percentile. What would that be, roughly speaking, in terms of a standard IQ measurement? I've been trying for years to find out my IQ and no one has told me. Thank you!
A: Different tests convert percentiles differently and we use a manual strictly to get the best possible estimates. The Slosson Intelligence Test (SIT) serves as a quick estimate of general verbal cognitive ability or index of verbal intelligence. This test was designed to facilitate the screening of children at risk (i.e., of educational failure) by providing a quick estimate of mental ability, and to identify children who may be appropriate candidates for deeper testing services (such as gifted children). This test is suitable for screening purposes, although it has been recommend that additional (short form) of other comprehensive intelligence test batteries that are more psychometrically sound be used for detailed understanding of general intelligence. The Cognitive Areas of Measurement include: Vocabulary, General Information, Similarities and Differences, Comprehension, Quantitative, Skills and Auditory Memory. It is at best used a decent quick estimate of intelligence.
Based on the percentile, you scored as well or better than 95% of individuals of the same age. This means that you would be in the top 5% range. I would think that based on the estimates then, you could have an IQ score of about 125, which places you in the Superior range of abilities. However, this is just my personal gauge based only on the percentile and should be viewed cautiously.
It is best to get the latest test done as tests these days are have higher reliability and validity. Furthermore, being a brief test, the SIT does not tell you much about your strengths and weaknesses. Good luck!
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