Which of the following best defines a z score?

A z score is a statistical measurement that indicates how many standard deviations a particular data point is from the mean of a dataset. It is calculated by taking the difference between the individual score and the mean, and then dividing by the standard deviation. This metric allows for understanding how unusual or typical a score is within the context of a distribution.

Using z scores, educators and researchers can make comparisons across different sets of data, even if the scales or units of measurement differ. This can be particularly useful in educational assessments, as it enables an understanding of how a student's performance compares to that of their peers.

The other choices do not accurately describe a z score. Student attendance is unrelated to statistical measurement of scores, the average score, or grade formulas. Instead, a z score specifically quantifies the distance from the mean in a standardized way, making option C the most accurate definition.