How to calculate standard deviation

Standard deviation (Std Dev, Standard Deviation) - a statistical term.

#A standard that measures the dispersion of data distribution, used to measure the degree to which data values ​​deviate from the arithmetic mean. The smaller the standard deviation, the less the values ​​deviate from the mean, and vice versa. The size of the standard deviation can be measured by the ratio of the standard deviation to the mean. (Recommended learning: web front-end video tutorial)

Standard deviation is also called standard deviation. Standard deviation (Standard Deviation) describes the distance (deviation from the mean) of each data from the mean. The mean, which is the square root of the average sum of squared deviations, is represented by σ.

The standard deviation is the arithmetic square root of the variance. Standard deviation reflects the dispersion of a data set. The smaller the standard deviation, the less the values ​​deviate from the mean, and vice versa. The size of the standard deviation can be measured by the ratio of the standard deviation to the mean. Two data sets with the same mean may not have the same standard deviation.

Calculation steps

The calculation steps for sample standard deviation are:

Step 1. (Subtract from each sample data average of all data in the sample).

Step 2. Add the squares of the values ​​obtained in step 1.

Step 3. Divide the result of step 2 by (n - 1) ("n" refers to the number of samples).

Step 4. The square root of the value obtained from step 3 is the standard deviation of sampling.

The steps for calculating the population standard deviation are:

Step 1. (Each sample data subtracts the average of all the population data).

Step 2. Add the squares of the values ​​obtained in step 1.

Step 3. Divide the result of step 2 by n ("n" refers to the overall number).

Step 4. The square root of the value obtained from step 3 is the overall standard deviation.

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