# Standard Deviation {% hint style="success" %} Standard Deviation is a measure of how spread out numbers are. {% endhint %} It is the square root of the [Variance](/statistics/variance.md). It is often more convenient than the variance because it has the same unit as the data points. **Population Standard Deviation**, $$\sigma=\sqrt{\frac{1}{n}}\sum\_i^n(x\_{i}-\mu)^2$$ **Sample Standard Deviation**, $$\sigma=\sqrt{\frac{1}{1-n}}\sum\_i^n(x\_{i}-\overline{x})^2$$ --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://ai.nuhil.net/statistics/standard-deviation.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.