The Excel F.TEST function returns the FTest for two supplied arrays. I.e. the function returns the twotailed probability that the variances in the two supplied arrays are not significantly different.
The F.TEST function is new to Excel 2010. However, this is simply a renamed version of the Ftest function, which is available in earlier versions of Excel.
The syntax of the F.Test function is:
where the supplied array1 and array2 are two arrays of data values that represent samples from two different populations. If the arrays contain text, logical values or empty cells, these are ignored.
A  B  C  

1  Group 1  Group 2  
2  3.5  9.2  =F.TEST( A2:A11, B2:B11 ) 
3  4.7  8.2  
4  6.2  7.3  
5  4.9  6.1  
6  3.8  5.4  
7  5.5  7.8  
8  7.1  5.9  
9  6.7  8.4  
10  3.9  7.7  
11  4.6  6.6 
Columns A and B of the above spreadsheet on the right contain the reaction times of a sample of individuals from two different groups.
Cell C2 of the spreadsheet shows the use of the Excel F.TEST function to calculate the probability that there is no significant difference between the variances of the two data sets.
The result of the F.Test function in cell C2 is 0.954035559.
Further details and examples of the Excel F.Test function are provided on the Microsoft Office website.
If you get an error returned from the Excel F.Test Function, this is likely to be the Excel #DIV/0! error:
#DIV/0!    Occurs if either:
