What is a primary use of standardization, such as z-scores, in normative testing?

What is a primary use of standardization, such as z-scores, in normative testing?

• A. To create entirely new scales.
• B. To reduce sample size.
• C. To remove age and sex effects.
• D. To ensure comparability across tests with different scales.

Answer: (D)

Standardization with z-scores puts different test scores onto a common metric by using the normative distribution. A z-score shows how many standard deviations a raw score is from the mean, so regardless of the test’s original units or scale, scores can be interpreted in the same way. This makes it possible to compare performance across tests that use different scales, because every score is expressed relative to the same reference distribution. It doesn’t create new scales from scratch, nor does it inherently reduce sample size. While norms can be tailored by age or sex to reflect expected differences, the essential purpose of standardization is to enable comparability across tests with different scales.

Standardization with z-scores puts different test scores onto a common metric by using the normative distribution. A z-score shows how many standard deviations a raw score is from the mean, so regardless of the test’s original units or scale, scores can be interpreted in the same way. This makes it possible to compare performance across tests that use different scales, because every score is expressed relative to the same reference distribution. It doesn’t create new scales from scratch, nor does it inherently reduce sample size. While norms can be tailored by age or sex to reflect expected differences, the essential purpose of standardization is to enable comparability across tests with different scales.