The Excel T.TEST function calculates the probability associated with the Student's T Test, which is commonly used for identifying whether two data sets are likely to have come from the same two underlying populations with the same mean.
The T.TEST function is new to Excel 2010. However, this is simply a renamed version of the TTEST function, which is available in earlier versions of Excel.
The format of the T.Test function is:
where the function arguments are:
|array1||-||The first data set.|
|array2||-||The second data set (must have the same length as array1).|
Columns A and B of the above spreadsheet on the right contain two arrays of data.
The probability associated with the Student's paired t-test with a one-tailed distribution, for the two arrays of data can be calculated using the Excel T.Test function as follows:
This gives the result 0.449070689.
The probability associated with the Student's paired t-test with a two-tailed distribution, for the same two arrays of data, is calculated as follows:
This gives the result 0.898141379.
Note that the probability associated with the two-tailed T-Test is double that of the one-tailed T-Test.
Further information and examples of the Excel T.Test function are provided on the Microsoft Office website.
If you get an error from the Excel T.Test Function, this is likely to be one of the following:
|#N/A||-||Occurs if the two supplied arrays have different lengths.|
|#VALUE!||-||Occurs if either the tails argument or the type argument is non-numeric.|