What does standard deviation measure in a set of numbers?

Standard deviation is a statistical measure that quantifies the amount of variation or dispersion in a set of numbers. It specifically indicates how much individual scores differ from the mean (average) score of the dataset. A low standard deviation suggests that the scores tend to be close to the mean, while a high standard deviation indicates that the scores are spread out over a wider range. This is crucial in understanding the distribution of data and assessing how consistent or variable the scores are within a group, which can provide insights into performance levels in various assessments, including those relevant to educational testing for students who are deaf or hard of hearing. The other options do not accurately describe what standard deviation measures, as they focus on averages, participant counts, and ranges rather than the concept of variability around the mean.