Reliability—The consistency of results produces by measurement devices.
Percentile—The percent of norm group students who had lower scores than the
student being tested
Norm Group—The group of test-takers whose scores are used to make relative
interpretations of others’ test performances.
Validity—The extent to which a test measures what its authors or users claim it
measures. The accuracy of the inferences or interpretations that are made based on
students’ performances on measurement devices.
Standard Deviation—A measure of the degree of dispersion in a distribution
Standard Error of Measurement (SEM)—The consistency of an individual’s test
performance.
Mean—The statistical average of a set of scores in a distribution.
Median—A score that divides the top 50% of test takers from the bottom 50%. The
point on a scale above which 50% of the cases occur above and below that point.
Mode—The most frequently obtained score in a distribution