RELIABILITY & VALIDITY EXPLAINED Do those dart boards seem familiar? In this video we will explain what reliability and validity (=accuracy, what we talked about in the last 4 episodes) are and how they relate to one another. When the term reliability is used, one can distinguish between the two basic forms: 1) Intra-rater reliability: How reproducible are results within one tester/observer 2) Inter-rater reliability: How reproducible are results between two (or more) testers/observers | Physiot