True score theory

True score theory, used in testing and assessment, suggests that every person's observed test score is made up of two parts: their true ability (or true score) and some error (like guessing or distractions). The true score reflects their actual knowledge or skill, while the error is random and unavoidable. The goal of testing is to estimate the true score as accurately as possible, minimizing the impact of error. This theory helps in understanding the reliability of test results and in designing assessments that better reflect a person’s true abilities.