juniorProbability
What is the difference between variance and standard deviation?
Updated May 17, 2026
Short answer
Variance is the average squared deviation, while standard deviation is its square root.
Deep explanation
Variance is expressed in squared units, which can be unintuitive. Standard deviation brings the measure back to original units, making interpretation easier. Both measure spread, but standard deviation is more interpretable in real-world contexts.
Real-world example
In exam scores, standard deviation tells how much scores typically deviate from the mean.
Common mistakes
- Using variance directly for interpretation instead of standard deviation.
Follow-up questions
- Why take square root?
- Which is used more in reporting?