Standard Deviation accuracy and testing

Formula source

• The calculator performs the following steps: 1. Calculates the **Mean** (average). 2. Subtracts the Mean from each number and squares the result. 3. Finds the average of those squared differences (this is the **Variance**). *Note: Divides by N for Population, or N-1 for Sample.* 4. Takes the square root of the Variance to get the **Standard Deviation**.

Test cases

Known limitations

• This page documents the checked-in calculator logic and does not certify results for every real-world edge case.
• Use the result as a planning estimate unless the calculator page states a stricter purpose.

Assumptions

• The dataset should contain numeric values only, entered as a comma- or space-separated list.
• Choose Sample when your list is a subset of a larger population and Population when it includes every observation of interest.
• Standard deviation is non-negative and becomes more sensitive when outliers are present.

Unit handling

• Data Set accepts text values.
• Type accepts one of the configured options.

Rounding rules

• Number displays use up to 2 decimal places in the calculator UI.

Version history

Change log