Discrimination is the spread of scores produced by a test, or the extent to which a test separates students from one another on a range of scores from high to low. Also used to describe the extent to which an individual multi-choice item separates the students who do well on the test as a whole from those who do badly.

Difficulty is the extent to which a test or test item is within the ability range of a particular candidate or group of candidates.

Mean is a descriptive statistic, measuring central tendency. The mean is calculated by dividing the sum of a set of scores by the number of scores.

Median is a descriptive, measuring central tendency: the middle score or value in a set.

Marker, also scorer is the judge or observer who operates a rating scale in the measurement of oral and written proficiency. The reliability of markers depends in part on the quality of their training, the purpose of which is to ensure a high degree of comparability, both inter- and intra-rater.

Mode is a descriptive statistic, measuring central tendency: the most frequent occurring score or score interval in a distribution.

Raw scores – test data in their original format, not yet transformed statistically in any way ( eg by conversion into percentage, or by adjusting for level of difficulty of task or any other contextual factors).

Reading comprehension test is a measure of understanding of text.

Reliability is the consistency, the extent to which the scores resulting from a test are similar wherever and whenever it is taken, and whoever marks it.