In Excel 2010, the STDEV function has been replaced by the STDEV.S function, which has improved accuracy.
The Excel STDEV function calculates the sample standard deviation of a supplied set of values.
The format of the function is :
where the arguments, number1, [number2], etc, are between 1 and 255 numerical values, arrays of values, or references to cells containing numbers. These must provide at least two numerical values to the function.
If you are using Excel 2007 a later version of Excel you can enter up to 255 number arguments to the function. However, in Excel 2003, the function can only accept up to 30 number arguments.
Note that the Stdev function is used when calculating the standard deviation for a sample of a population (eg. if your data set records the individual heights of a sample of UK males). If you are calculating the standard deviation of an entire population, you need to use the Stdevp function.
Note also, that the Stdev function ignores text values and logical values if these are supplied as part of an array. If you want a function that includes text and logical values in the calculation, consider using the Stdeva function.
Imagine you wanted to find out the standard deviation of the heights of adult males in London. It is not realistic to measure the height of all males, but you could take a sample of the population and measure their heights.
The example spreadsheet on the right stores the measurements (in cm) of 3,000 adult males. The measured heights are stored in cells B3 - B1002, D3 - D1002 and F3 - F1002.
As shown in cell H3, the standard deviation in the individual heights of the sample group is 5.4 cm.
In the example above, the arguments to the Stdev function are input as 3 cell ranges. However, you can also input figures directly, as individual numbers or number arrays.
For example, if you wanted to include two further heights, of 176cm and 177cm into the sample, you could add these directly into the above function as follows:
Further information and examples of the Excel Stdev function can be found on the Microsoft Office website.
If you get an error from the Excel Stdev function this is likely to be one of the following:
|#DIV/0!||-||(Note that text representations of numbers, that are supplied as a part of an array, are not interpreted as numeric values by the Stdev function)|
|#VALUE!||-||Occurs if any values that are supplied directly to the Stdev function are text values that cannot be interpreted as numeric values.|