The Excel FTEST Function

Ftest and F.Test

In Excel 2010, the Ftest function has been replaced by the F.Test function.

Although it has been replaced, the Ftest function is still available in Excel 2010, (stored in the list of compatibility functions), to allow compatibility with earlier versions of Excel.

However, the Ftest function may not be available in future versions of Excel, so it is advised that you use the F.Test function, if possible.

Function Description

The Excel FTEST function returns the F-Test for two supplied arrays. I.e. the function returns the two-tailed probability that the variances in the two supplied arrays are not significantly different.

The syntax of the Ftest function is:

FTEST( array1, array2 )

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 by the Ftest function.

Ftest Function Example

  A B C
1 Group 1 Group 2  
2 3.5 9.2 =FTEST( 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 Excel Ftest function used to show the probability that there is no significant difference between the variances of the two data sets.

The result of the Ftest function in cell C2 is 0.954035559.

For further details and examples of the Excel Ftest function, see the Microsoft Office website.

Ftest Function Error

If you get an error returned from the Excel Ftest Function, this is likely to be the Excel #DIV/0! error:

Common Error
#DIV/0! -

Occurs if either:

  • The number of values in either array1 or array2 is less than 2
  • The variance of array1 or array2 is equal to 0.