The standard deviation is:

The standard deviation is: (a) The square root of the variance

(b) A measure of variability

(c) An approximate indicator of how numbers vary from the mean

(d) All above

✅ Correct option: (d) All above

Explanation:

Standard deviation is one of the most important measures in statistics. It represents the average distance of scores from the mean and provides insight into data spread. Mathematically, standard deviation is the square root of variance. Conceptually, it indicates how much scores deviate from the mean. A small standard deviation indicates clustered data, while a large one indicates spread-out data. All listed statements accurately describe standard deviation, making “All above” the correct answer.

10 Related PPSC Facts:

Standard deviation measures dispersion. Variance is SD squared. SD is expressed in original units. SD is affected by extreme values. Used in z-scores. SD helps compare distributions. Larger SD indicates more variability. Zero SD means all scores identical. SD is central to inferential stats. Normal distribution relies on SD.