VARA function
Estimates variance based on a sample.
Syntax
VARA(value1,value2,...)
Value1, value2, ... are 1 to 255 value arguments corresponding to a sample of a population.
Remarks

VARA assumes that its arguments are a sample of the population. If your data represents the entire population, you must compute the variance by using VARPA.

Arguments can be the following: numbers; names, arrays, or references that contain numbers; text representations of numbers; or logical values, such as TRUE and FALSE, in a reference.

Logical values and text representations of numbers that you type directly into the list of arguments are counted.

Arguments that contain TRUE evaluate as 1; arguments that contain text or FALSE evaluate as 0 (zero).

If an argument is an array or reference, only values in that array or reference are used. Empty cells and text values in the array or reference are ignored.

Arguments that are error values or text that cannot be translated into numbers cause errors.

If you do not want to include logical values and text representations of numbers in a reference as part of the calculation, use the VAR function.

VARA uses the following formula:
where x is the sample mean AVERAGE(value1,value2,…) and n is the sample size.
Example
Suppose 10 tools stamped from the same machine during a production run are collected as a random sample and measured for breaking strength.
The example may be easier to understand if you copy it to a blank worksheet.
How to copy an example

Create a blank workbook or worksheet.

Select the example in the Help topic.
Note Do not select the row or column headers.
Selecting an example from Help

Press CTRL+C.

In the worksheet, select cell A1, and press CTRL+V.

To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.

