Positive Skew  Negative Skew 
For more information on skewness, see the Wikipedia page
The Excel SKEW function calculates the skewness of the distribution of a supplied set of values.
The format of the function is :
Where the number arguments provide a minimum of 3 values that make up the data set. These can be individual numbers or arrays of numbers and can be input either directly, as returned values from other functions or formulas, or as references to cells containing values.
In Excel 2007, you can input up to 255 number arguments to the Skew function, but in Excel 2003, you can only input up to 30 arguments.
A  B  

1  1  
2  1  
3  2  
4  2  
5  2  
6  2  
7  3  
8  3  
9  3  
10  4  
11  4  
12  5  
13  6  
14  7  
15  8 
Column A of the spreadsheet on the right shows 15 data values. The distribution of these values is shown in the chart below:
The skewness of the values in the spreadsheet can be calculated using the Excel Skew Function as follows:
This gives the result 0.863378312, indicating that the data set has a positive skew.
Further information and examples of the Excel Skew function can be found on the Microsoft Office website.
If you get an error from your Excel Skew function this is likely to be the Excel #DIV/0! error:
#DIV/0!   
Occurs if either:
