What is the Standard Deviation

 Standard Deviation (SD)- 

Under squre root of ,The sum of the squares of differences between individual QC values and the mean divided by number of all points - 1.

Here's how to calculate sample standar     deviation:

Step 1: Calculate the mean of the data—this is ( X̄ ) in the formula.

Step 2: Subtract the mean from each data point. These differences are called deviations. Data points below the mean will have negative deviations, and data points above the mean will have positive deviations.

Step 3: Square each deviation to make it positive.

Step 4: Add the squared deviations together.

Step 5: Divide the sum by one less than the number of data points in the sample. The result is called the variance.

Step 6: Take the square root of the variance to get the standard Deviation.