The standard deviation is the measure of the variance in a set of numbers compared to the mean or average of the numbers. The Excel STDEV function calculates the standard deviation of a set of numbers that represents a sample.
Figure 1. How to Use the Excel STDEV Function
The syntax for the Excel STDEV function is;
This function can have arguments between 1 and 255 maximum.
- number1 – It is required and the first argument of sample number
- number2,… – These are optional and additional arguments of sample numbers between 2 and 255.
The Excel STDEV function supports arguments that can be entered as numbers, arrays, ranges or cell references that may contain numeric, text, logical values, text representations of numbers and empty cells. It evaluates only numeric values in the calculation of standard deviation, ignoring the text, logical values (TRUE and FALSE), text representations of numbers and empty cells in ranges, arrays or cell references of a sample set of values. However, the logical and text representations of numbers supplied directly as the argument in function are evaluated as numbers.
Figure 2. The Syntax For the Excel STDEV Function
Suppose we have a sample dataset of monthly sales and we need to calculate the standard deviation based on this sample dataset. This estimate basically tells us how much monthly sales figures deviate from the average monthly sales of the sample. Following formula will be used to calculate a standard deviation of this sample;
Figure 3. Calculating the Standard Deviation of Sample
- The Excel STDEV function has been replaced by the STDEV.S function in Excel 2010 and later versions. It is now available for compatibility with Excel 2007 and earlier.
- It generates #DIV/0! error if all supplied arguments contain text values.
- If a text value is entered directly as an argument, it generates #VALUE! error.
Figure 4. Error Value of the STDEV Function
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