T.TEST Function

Calculate the probability that is associated with a Student’s T-Test

What is the T-TEST Function?

The T-TEST Function is categorized under Statistical functions. It will calculate the probability that is associated with a Student’s T-Test. It is commonly used to test the difference between two small sample sizes, specifically the difference between the samples when the variances of two normal distributions are not known.

In financial analysis, suppose we wish to understand the amount spent by Europeans and Americans on food. We cannot practically record the spending habits of every European and American, so we would take a sample of the entire population. In such scenario, T-test will help us find the answer to the question on whether the difference between the food spending of the two groups is representative of a true difference between Europeans and Americans in general or if it is just a meaningless statistical difference.





The formula uses the following arguments:

  1. Array1 (It is a required argument) – It is the first data set.
  2. Array2 (It is a required argument) – It is the second data set.
  3. Tails (It is a required argument) – It specifies the number of distribution tails. If tails = 1, T-TEST uses the one-tailed distribution. If tails = 2, T-TEST uses the two-tailed distribution.
  4. Type (It is a required argument) – It is the types of test to perform.


How to use the T-TEST Function in Excel?

To understand the uses of the T.TEST function, let’s consider a few examples:


Example 1 – Perform a T-Test calculation in Excel

Suppose we are given the following data on the money spent by households in Europe and the US.


T-TEST Function 


The probability associated with the Student’s paired t-test with a one-tailed distribution for the two arrays of data above can be calculated using the Excel function. The formula used is as follows:


T-TEST Function - Example 1


We get the result below:


T-TEST Function - Example 1a


Things to remember about the T-TEST Function 

  1. #NUM! error – Occurs when:
    • The given tails argument has any value other than 1 or 2.
    • The given type argument is not equal to 1,2 or 3.
  2. #N/A! error – Occurs when the two supplied arrays are of different lengths.
  3. #VALUE error – Occurs when either the given tails argument or the supplied type argument is non-numeric.


Click here to download the sample Excel file


Additional resources

Thanks for reading CFI’s guide to important Excel functions! By taking the time to learn and master these functions, you’ll significantly speed up your financial analysis. To learn more, check out these additional resources:

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