What Do These Test Scores Mean? Part 1
Here are some of the more commonly used cognitive assessments in schools:
- Wechsler Intelligence Scale for Children (WISC-IV)
- Differential Ability Scales (DAS-II)
- Stanford Binet Intelligence Scale (SB-V)
The cognitive assessment will have an overall IQ score. This score will be considered valid only if testing conditions were adequate and there is minimal variability in scores among the various scales on the assessment. When there is a significant scatter in the different areas, the overall score will not be representative of a child’s overall potential and one must look more closely at the scores in the Scales.
In addition to the overall IQ Score, the cognitive assessment will measure various processing areas. For example the WISC-IV measures Verbal ability, Nonverbal ability, Processing Speed, and Working Memory. The score in each area will indicate ability in the various areas measured. For example, the score in Processing Speed on the WISC-IV will indicate a person’s ability to quickly and accurately process simple visual information.
The scores are obtained in a complicated and statistical way, not the percentage of questions answered correctly. Thousands of people were given the assessment and the results were standardized to determine various ranges of ability. With the results of the sample population, norms were created. Percentile rankings were correlated with a person’s performance level based on the norms created from the standardized sample. Your child’s score will be a comparison of how he or she performed compared to the standardized sample. 68 % of the population will perform in the Average range. The farther away from the Average range one performs, the less typical the scores are.
The scores are typically described in Standard Scores. Standard Scores have a mean (Average of 100.) Anything within a 10 points from 100 is considered Average. Scores from about 90-110 are considered average. Some assessments will vary slightly. Just outside of that range is the Low Average range (80-89) and the High Average range (110-119). Students performing in either of these ranges are slightly different from the norm, but still within expectations of the general public. High Average scores suggest somewhat stronger cognitive abilities while a person with Low Average scores may struggle somewhat to keep up. The Borderline range is 70-79. Students in this range may significantly struggle in the classroom. However, they often will not qualify for special education services. Remediation or other strategies should be considered. Below 70 would be the Extremely Low range indicating a possibility of an Intellectual Disability or Mental Retardation (the scores alone will not diagnose). Three percent of the population will fall in this range. On the other end three percent of the population is estimated to fall in the gifted or Superior range (130 and above). Scores between 120-129 are considered Above Average.
The scales are comprised of a few individual tasks that measures differing aspects of the processing area. The student’s performance on the task is measured with a Scaled Score. The Average range on Scaled Score is 8-12.
In summary, scores on the cognitive assessment are actually intended to be a comparison to the general public. Think of the scores in terms of ranges. First look at the overall IQ score and determine if that is a valid estimate of his ability. Second, look at each of the Scales to see how he performed in the various processing areas. Third, look at the individual tasks within the the scales. Ask your School Psychologist for information as to what each of the tasks and scales measure.