Standard Score (SS): A way to compare student performance to a standardization sample.  Standard Scores in evaluation reports have a Mean (average) of 100 and a Standard Deviation of + or - 15.  A standard deviation (SD) is a measure used to quantify the amount of variation from the Mean.  A lower SD indicates a student performing closer to the majority with a higher SD indicating performing much lower or higher than the majority. 66% of students will score between 85 and 115. 

Scale Scores: have a score range of 0 – 19 points, with an average score of 10 points. These scores are typically used for “Sub-tests,” which are smaller components of a larger psychological test, such as the WISC-V, the NEPSY-2, or the DKEFs.

T Scores: are standardized scores on each dimension for each type. A score of 50 represents the mean. A difference of 10 from the mean indicates a difference of one standard deviation. Thus, a score of 60 is one standard deviation above the mean, while a score of 30 is two standard deviations below the mean.

Percentile Rank: of a score is the percentage of scores in its frequency distribution that are equal to or lower than it. For example, a test score that is greater than 75% of the scores of people taking the test is said to be at the 75th percentile rank. Percentile ranks are not on an equal-interval scale; that is, the difference between any two scores is not the same between any other two scores whose difference in percentile ranks is the same.