Which statistic represents the precision of an individual score and is used to quantify measurement error?

Which statistic represents the precision of an individual score and is used to quantify measurement error?

• A. Pearson's r
• B. Cohen's Kappa
• C. Standard error of measurement (SEM)
• D. Spearman's Rho

Answer: (C)

The precision of an individual score and the amount of measurement error are captured by the standard error of measurement (SEM). SEM reflects how much an observed score would be expected to differ from the true score if the measurement were repeated with the same instrument. It scales with the test’s variability and its reliability—the higher the reliability, the smaller the SEM, meaning more precise scores. SEM is useful for interpreting where a person’s true ability or trait likely lies and for constructing confidence intervals around an observed score to estimate the range of the true score. The other statistics address different questions: Pearson's r and Spearman's rho describe relationships between two variables, not the precision of a single measurement, and Cohen's Kappa assesses agreement between raters for categorical judgments, not measurement error for a continuous score.

The precision of an individual score and the amount of measurement error are captured by the standard error of measurement (SEM). SEM reflects how much an observed score would be expected to differ from the true score if the measurement were repeated with the same instrument. It scales with the test’s variability and its reliability—the higher the reliability, the smaller the SEM, meaning more precise scores. SEM is useful for interpreting where a person’s true ability or trait likely lies and for constructing confidence intervals around an observed score to estimate the range of the true score. The other statistics address different questions: Pearson's r and Spearman's rho describe relationships between two variables, not the precision of a single measurement, and Cohen's Kappa assesses agreement between raters for categorical judgments, not measurement error for a continuous score.