VARA

Estimates variance based on a sample.

Syntax

VARA(value1,value2,...)

Value1, value2, ...     are 1 to 30 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:

Equation

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.

ShowHow 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

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.
 
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A
Strength
1345
1301
1368
1322
1310
1370
1318
1350
1303
1299
Formula Description (Result)
=VARA(A2:A11) Estimates the variance for the breaking strength (754.2666667)
 
 
Applies to:
Excel 2003