Mathematics
What is Standard deviation?
Standard deviation is a number that tells you how spread out data is around its average. A small standard deviation means values cluster close to the mean; a large one means they're scattered widely.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains standard deviation.
Key things to understand
- 1It measures how far data points typically sit from the average.
- 2Low value = tightly clustered data; high value = widely spread.
- 3It's the square root of the variance.
- 4It's used everywhere from test scores to finance and quality control.
Frequently asked questions
- What does standard deviation tell you?
- How spread out a set of numbers is around their average value.
- Is a high or low standard deviation better?
- Neither is inherently better — it depends on context. Low means consistency; high means variety or risk.
- How is standard deviation related to variance?
- Standard deviation is the square root of the variance, putting the spread back into the data's original units.