Which score is expressed in standard deviation units from the mean?

Which score is expressed in standard deviation units from the mean?

• A. Standard scores
• B. Percentile ranks
• C. Z-scores
• D. Raw scores

Answer: (C)

Z-scores express a value in standard deviation units from the mean. By subtracting the mean and dividing by the standard deviation, any score is placed on a standard scale with a mean of 0 and an SD of 1, allowing direct comparison across different tests. Percentile ranks indicate relative position but not distance in SD units, and raw scores are simply the original measurements. Standard scores refer to transformed scores with a fixed mean and SD (such as IQ scales), but they aren’t inherently expressed in SD units the way z-scores are. So the score expressed in standard deviation units from the mean is the z-score.

Z-scores express a value in standard deviation units from the mean. By subtracting the mean and dividing by the standard deviation, any score is placed on a standard scale with a mean of 0 and an SD of 1, allowing direct comparison across different tests. Percentile ranks indicate relative position but not distance in SD units, and raw scores are simply the original measurements. Standard scores refer to transformed scores with a fixed mean and SD (such as IQ scales), but they aren’t inherently expressed in SD units the way z-scores are. So the score expressed in standard deviation units from the mean is the z-score.