Reliablity & Validity Lesson Five:Classical Test Theory (CTT) These two videos might help you understand validity and reliability better: That is, if the testing process were repeated with a group of test takers, essentially the same results would be obtained (Reliability, 2018). Scores that are highly reliable are accurate, reproducible, and consistent from one testing occasion to another. 'It is the characteristic of a set of test scores that relates to the amount of random error from the measurement process that might be embedded in the scores. A measure is said to have a high reliability if it produces similar results under consistent conditions. Reliability is the overall consistency of a measure. The modern validity can be analyzed with six different aspects, which are content, process, structural, generalizability, external, and consequential aspects (Messick, 1995). The current definition of validity is a unified concept, under the construct framework, which addresses both the score meaning and the score usage (Messick, 1995). Validation is the joint responsibility of both test developers and test-takers (American Educational Research Association et al., 2014). The process of gathering evidences to support the appropriateness of interpreting test scores and using the scores to make decision is test validation. In the current conception, validity is the degree to which evidences and theories support the adequacy and appropriateness of interpreting test scores and making certain decision according to the test score (Messick, 1995 American Educational Research Association, American Psychological Association, & National Council on Measurement in Education, 2014). Validity of psychological assessment: Validation of inferences from persons' responses and performances as scientific inquiry into score meaning. Educational measurement: Issues and practice, 10(1), 37-45. In this unit, we are going to talk about:ġ, What is validity and reliability, and how to evaluate an assessment with these two definitions

3 Lesson Five:Classical Test Theory (CTT).

2 Lesson Four: Validity and Reliability.

Reliability in psychological testing