Basics of School Psychology Flashcards
(7 cards)
Percentile Score
This refers to the percentage of scores (students) in a frequency distribution that are equal to or lower than the percentile score. An example is a student with a score in the 33rd percentile who has scored better than or equal to 33% of those who took the same test. Percentiles are not an equal interval measurement; they cluster toward the mean. This can be confusing to lay people who think percentiles are percentages.
Grade norms and equivalents
Students are matched to grade groups whose performance they equal. Average scores are obtained from individuals in a grade and compared with the grade group that their performance matches. An example is a student with a grade equivalent of 3.5, which means the student is performing as an average child in the fifth month of her third-grade year. Caution: Grade-equivalent scores should rarely be used because they are considered poor metrics.
Age norms and equivalents
Age equivalents (AEs) are similar to grade equivalents. An individual is matched to the AE whose performance they equal. AE is the average score earned by individuals at a specific age. As with other unequal interval metrics, this type of score should be used with a high degree of caution.
Standard scores (SSs)
SSs are psychometrically sound measures and are used to describe a person’s position within the normal curve (bell curve) of human traits compared to same-age peers. These scores express the position of a score in relation to the average (mean) of other scores. SSs use standard deviations (SDs) in their formulas and place a student’s score as below average, average, or above average. Mainstream cognitive test batteries typically use an SS with a mean of 100 and an SD of 15 (e.g., SS = 85–115 is average).
T-scores
T-scores are commonly used. They have a mean of 50 and an SD of 10 (T = 40–60 is average).
Scaled scores (Ss)
Ss are commonly used for subtest scores. They have a mean of 10 with an SD of 3 (Ss = 7–13 is average)
