How to Calculate a Sigma Value

How to Calculate a Sigma Value
••• benjaminec/iStock/GettyImages

A sigma value is a statistical term otherwise known as a standard deviation. Determining the standard deviation of a set of values helps a statistician or researcher to determine if the data set is significantly different than a control set. Sigma is a measurement of variability, which is defined by the Investor Words website as "the range of possible outcomes of a given situation."

    Add a set of data and divide by the number of values in the set to find the mean. For instance, consider the following values: 10, 12, 8, 9, 6. Add them to get a total of 45. Divide 45 by 5 to get a mean of 9.

    Subtract the mean from each individual value. In this example, you would perform the following operations: 10 - 9 = 1 12 - 9 = 3 8 - 9 = -1 9 - 9 = 0 6 - 9 = -3

    Square each answer from step two.

    In this example: 1 x 1 = 1 3 x 3 = 9 -1 x -1 = 1 0 x 0 = 0 -3 x -3 = 9

    Add your answers from step three. For this example, add 1, 9, 1, 0 and 9 to get a total of 20.

    Subtract one from the sample size. The sample size here is 5, so 5 - 1 = 4.

    Divide the total from step four by your answer from Step 5. Therefore, you would divide 20 by 4 to get 5.

    Take the square root of your answer from step six to find the sigma value or standard deviation. For this example, you would take the square root of 5 to find a sigma value of 2.236.

Related Articles

How to Calculate Statistical Mean
How to Calculate the Distribution of the Mean
How to Find Correlation Coefficient & Coefficient of...
How to Solve for Range
How to Calculate the Confidence Interval of the Mean
How to Calculate Percent Relative Range
How to Calculate CV Values
How to Find Y Value for the Slope of a Line
Test Your Knowledge on Middle School Science
How to Find a Z Score
How to Find the Missing Side of a Right Triangle
How to Factorise a Quadratic Expression
How to Get the Average of Decimals
How to Calculate the Grand Mean
How to Find the Missing Number of the Given Mean
Define Mean for Math
How to Calculate a T-Statistic
How to Type a Mixed Fraction in a TI-83 Plus
How to Calculate Regression Coefficient
How to Calculate a Temperature Range