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Variance and Standard Deviation
Creating the Equivalent

Variance and Standard Deviation are two statistical calculations that are frequently used to analyze data. The formulae below derive Variance and Standard Deviation:

To find the Standard Deviation of a set of records, use the following technique. In this example, there are two Relations: one Relation with one record per sample set, and another Relation to store the samples. In the Relation which contains the sample records, create a "Sub-Average" Abacus:

Also create an Abacus to calculate the square of the difference between the sample value and the Sub-Average (Mean Diff. Sq.):

In the "Sample Set" Relation, create:

1. An Abacus to find the Sub-Count (n) of the sample records:

2. An Abacus to find the Sub-Total of the Mean Diff. Sq. Abacus:

3. An Abacus to calculate the Variance:

4. An Abacus to calculate the Standard Deviation:

Place the "Variance" and "Standard Deviation" Abacii on the forms in the "Sample Set" Relation where you wish to view this information.