How should confidence intervals around an individual's test score be interpreted?

How should confidence intervals around an individual's test score be interpreted?

• A. They indicate the test's internal consistency
• B. They estimate the test's maximum score
• C. They indicate the range within which the true score likely falls with a specified level of confidence
• D. They reflect the test's validity

Answer: (C)

Confidence intervals around an individual's test score express the range where their true score is likely to fall, given measurement error. In classical test theory, an observed score = a true score plus random error. Because the error varies, the true score cannot be known exactly from a single test administration. A confidence interval provides a range that, at a chosen confidence level (for example, 95%), is expected to contain the true score. The width of this interval depends on the standard error of measurement, which is determined by the test’s reliability and score variability. A more reliable test yields a smaller standard error and thus a narrower interval, indicating greater precision. For instance, if someone scores 78 and the standard error is about 3, a 95% confidence interval around the true score would roughly span from 72 to 84. This interpretation focuses on where the true ability likely lies, not on the test’s internal consistency, maximum score, or validity.

Confidence intervals around an individual's test score express the range where their true score is likely to fall, given measurement error. In classical test theory, an observed score = a true score plus random error. Because the error varies, the true score cannot be known exactly from a single test administration. A confidence interval provides a range that, at a chosen confidence level (for example, 95%), is expected to contain the true score. The width of this interval depends on the standard error of measurement, which is determined by the test’s reliability and score variability. A more reliable test yields a smaller standard error and thus a narrower interval, indicating greater precision. For instance, if someone scores 78 and the standard error is about 3, a 95% confidence interval around the true score would roughly span from 72 to 84. This interpretation focuses on where the true ability likely lies, not on the test’s internal consistency, maximum score, or validity.