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How to Find the Sample Variance of a Data Set

Sample variance is a statistical test that you can calculate in order to explain the behavior of data found within a sample, or set, of numerical data. The sample data is most often generated by the results from a survey or laboratory experiment. Calculating the sample variance measures how much the actual results differ from the expected results. Sample variance is one of several calculations that you can use to describe a probability distribution.

Instructions

- 1
  Find the mean, or average, of the sample by dividing the total sum of the data by the number of data points in the sample.
- 2
  Subtract the mean from the first number in the sample and square the result. Repeat this step for every number in the sample.
- 3
  Add all of the squared values calculated in Step 2 together.
- 4
  Count the number of data points in the sample and subtract 1.
- 5
  Divide the summed value calculated in Step 3 by the number of values calculated in Step 4. The result is the sample variance.

Numerology