What does statistical reliability refer to in the context of assessment?

Statistical reliability in the context of assessment is fundamentally about the consistency of a test's results when it is administered multiple times. This means that if the same students take the same assessment on different occasions, a reliable test should yield similar results each time, assuming the students' knowledge and skills haven't significantly changed between administrations.

High reliability indicates that the assessment effectively measures the intended knowledge or skills consistently, providing educators with confidence in the results. This consistency helps to ensure that variations in scores are due to actual differences in student performance rather than fluctuations in the test itself.

In contrast, variability in student performance pertains to the differences in results among students and does not directly address the reliability of the testing tool. The accuracy of the measurement tool focuses on how well the test measures what it is supposed to measure, which is distinct from the stability of those measurements. Bias in test items relates to the fairness of the assessment and whether certain groups of students may be disadvantaged due to the content or structure of the test, rather than its consistency.