What term describes the margin of error expected in an individual's test score?

The margin of error expected in an individual's test score is referred to as the "error of measurement." This term encapsulates the uncertainty inherent in test scores, indicating how much an observed score may vary from the true score due to various factors, such as test reliability, testing conditions, and individual differences. Understanding the error of measurement is crucial in assessing the accuracy and consistency of test results, as it provides insight into how much confidence can be placed in a particular score.

Other terms in the question have specific meanings that are distinct from the error of measurement. The reliability coefficient quantifies the consistency of a test across different administrations or versions but does not directly express the margin of error in a particular individual score. The standard deviation measures the amount of variation or dispersion in a set of scores but does not specifically define the error margin for an individual test score. A confidence interval provides a range of values within which an individual's true score is likely to fall, but it is a broader statistical concept that is derived from the error of measurement and is not synonymous with it. Thus, the term that most accurately describes the expected margin of error in an individual's test score is the error of measurement.