What is the mean value of the Z-score statistic?

• A. 10
• B. 25
• C. 0
• D. 50

Answer: (C)

The mean value of the Z-score statistic is 0. This is because a Z-score represents the number of standard deviations a data point is from the mean of a distribution. By definition, the Z-score is calculated by subtracting the mean from a value and then dividing by the standard deviation. As a result, when you take the average of all Z-scores for a normally distributed dataset, the mean of these Z-scores equals 0. This characteristic is fundamental to Z-scores, as it indicates that the distribution of Z-scores is centered around 0, reflecting the statistical property of normal distributions.

Understanding that Z-scores have a mean of 0 helps in interpreting statistical data and is vital when conducting data analysis that involves standardization or comparison of scores in different datasets.