Look for the overall score, called Full Scale IQ score, which is the sum of the four index scores and reflects the tester’s verbal and performance abilities. Based on the Wechsler test conversion tables, a Full Scale score between 90 and 110 is considered average. A score of 130 and above is considered gifted. A score of 70 and below is considered learning disabled.
Find the composite score for each of the four indexes. These are Verbal Comprehension Index, Perceptual Reasoning Index, Working Memory Index, and Processing Speed Index. A description of each index may be found on various websites, including Concord Sped PAC (see Resources). The average intelligence score for each index is 100, with a standard deviation of 15. This means that any score within 15 points of 100 is considered normal.
Check the percentile rank, which shows how your child scored when compared to other children her age or grade. For example, if your child’s percentile mark for Verbal Comprehension is 79, it means that she scored higher than approximately 79 out of 100 children her age on tasks that require understanding of verbal information, thinking with words and expressing thoughts in words.
Find the confidence interval alongside the scores. Because test scores are not perfect, confidence intervals are used to provide a reasonably good estimate of a tester’s “true score.” In WISC, the confidence interval is 95 percent. This means that you can be 95 percent confident that your child’s true IQ score falls within a certain range. For example, if your child receives a score of 127, his true score is within the range of 122 to 132.