Standard Deviation

A way of expressing how much a normally distributed sample of scores is spread out. Nearly all of any sample of scores are contained in the range Mean plus or minus 3 Standard Deviations.

Standard Age Score or Standard Score

A standard score scale in which the mean score for each age group on an assessment is set at 100 and the standard deviation at 15. For any age group a given numerical value has the same meaning in terms of standing relative to the group. For example, an eight-year-old and a nine-year-old, each of whom has a standard age score of 105, have performed equally well in relation to the average for their respective age groups.


A test’s reliability concerns the consistency with which it measures whatever it is supposed to be measuring. A reliable assessment is dependable and will yield similar results each time it is used. Perfect reliability is represented by reliability coefficient of 1.0 but in practice this is never achieved although figures upwards off about 0.85 are commonly obtained.

Record of Achievement

A report on an individual child’s learning and development, compiled by the school. The report includes details of child’s progress in relation to the National Curriculum in England, Wales and Northern Ireland, and the 5-14 Guidelines in Scotland, but also reports on other aspects of the child’s overall experience of education.

Reading Age

This tells you the current developmental level of a child’s performance in a particular area of reading, such as comprehension, or word recognition skills. For example, a nine-year-old child with a reading age of nine is performing at the national average level for his or her age. Another child aged nine years, with the reading age of 10, is developmentally 12 months ahead of his or her peers in reading.

Raw Score

A score on assessment which is expressed simply as a total of the marks obtained on the test.


Literally, pertaining to mind and language. The study of mental processes that underlie the acquisition and use of language.


A profile based on assessment results, which provides a clear visual check on each child’s performance in an assessment or a series of assessments.  It enables strengths and needs to be easily identified. Performance in successive testing can be compared and skills can be contrasted with abilities.

Predictive Validity

Extent to which a test predicts ability in the same or similar areas in the future. For example, a test might be correlated with examination success (usually expressed in the terms of a correlation coefficient).