Excel 2007 Standard Deviation (STDEV) Function

The standard deviation is a statistical tool that tells you roughly how far, on average, each number in your list of data varies from the average value of the list itself.

Since standard deviation and average are so closely linked, the step by step example for this tutorial includes how to find the average value as well as the standard deviation for a list of numbers.

Related tutorial: Excel AVERAGE Function

The syntax for the Standard Deviation function is:

= STDEV ( Number1, Number2, ... Number255)

Number1, Number2, ... Number255 can be numbers or cell references to a list of data. Up to 255 arguments can be entered.

Example Using Excel's STANDARD DEVIATION and AVERAGE Functions:

For help with this example, see the image above.

1. Enter the following data into cells E1 to E6: 11, 12, 13, 14, 15, 16.
   
   
2. In cell D7 enter the heading Average: and in cell D8 Std Dev:

Calculating the Average Value

1. Click on cell E7 - the location where the AVERAGE function will be entered.
   
   
2. Click on the Formulas tab.
   
   
3. Choose More Functions > Statistical from the ribbon to open the function drop down list.
   
   
4. Click on AVERAGE in the list to bring up the function's dialog box.
   
   
5. Drag select cells E1 to E6 in the spreadsheet to enter the range into the dialog box.
   
   
6. Click OK.
   
   
7. The answer 13.5, which is the average value for the data in cells E1 to E6, should appear in cell E7.

Calculating the Standard Deviation

1. Click on cell E8 - the location where the STDEV function (standard deviation) will be entered.
   
   
2. Click on the Formulas tab.
   
   
3. Choose More Functions > Statistical from the ribbon to open the function drop down list.
   
   
4. Click on STDEV in the list to bring up the function's dialog box.
   
   
5. Drag select cells E1 to E6 in the spreadsheet to enter the range into the dialog box.
   
   
6. Click OK.
   
   
7. The answer 1.870828693 should appear in cell E7.
   
   
8. This number (approximately 1.87) represents the standard deviation of each number in the list from the average value of 13.5.
   
   
9. When you click on cell E8 the complete function = STDEV ( E1:E6 ) appears in the formula bar above the worksheet.

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