Which statistic tells where a score lies relative to the population mean, with a positive value indicating above the mean?

• A. Grade Equivalent
• B. Standard Score (z score)
• C. Percentile Rank
• D. Reliability

Answer: (B)

A standard score, or z score, is the statistic that shows where a score lies relative to the population mean in units of the standard deviation. It is calculated as (score minus the mean) divided by the standard deviation, so it standardizes different tests onto a common scale with a mean of 0 and a standard deviation of 1. A positive z score means the score is above the mean, a negative one means it’s below. This makes it easy to compare performances across different tests or populations because you’re measuring distance from the mean in standard deviation units.

Grade Equivalent describes a supposed grade level rather than distance from the mean and can be misleading. Percentile Rank tells you what percentage of scores fall below a given score, not how far that score is from the mean. Reliability concerns how consistently a measure yields the same result across occasions, not the position of a score within the distribution.