Plain-language meaning
A low standard deviation means values are closer to the mean. A high standard deviation means values are more spread out.
Sample vs population
Population standard deviation divides by n. Sample standard deviation divides by n - 1 to estimate population spread from a sample.
How it affects calculator results
The sample/population choice changes the denominator and can noticeably change the result for small datasets. The result also depends on the mean, so strong outliers can increase standard deviation sharply.
What to check
- Use sample standard deviation when your data is only a sample from a larger group.
- Use population standard deviation only when the dataset contains every value you care about.
- Look at the data shape and outliers before interpreting spread.
FAQ
Is a higher standard deviation always bad?
No. It only means values are more spread out. Whether that is good or bad depends on the context.
Why does sample standard deviation divide by n - 1?
Dividing by n - 1 helps reduce bias when estimating population spread from a sample.