What Is Standard Deviation? Standard deviation is a statistical measurement that looks at how far individual points in a dataset are dispersed from the mean of that set. If data points are further from the mean, there is a higher deviation within the data set. It is calculated as the square root of the variance.
Key Takeaways: Standard deviation measures the dispersion of a dataset relative to its mean. It is calculated as the square root of the variance. Standard deviation, in finance, is often used as a measure of the relative riskiness of an asset. A volatile stock has a high standard deviation, while the deviation of a stable blue-chip stock is usually rather low. Standard deviation is also used by businesses to assess risk, manage business operations, and plan cash flows based on seasonal changes and volatility.