# TTEST

Formulas / TTEST
Calculate the probability associated with the Student's T Test.
`T.TEST(array1,array2,tails,type)`
• array1 - required first data set
• array2 - required second data set
• tails - required number of distribution tails
• type - required t-Test type

## Examples

• `=TTEST( A1:A12, B1:B12, 1, 1 )`

The TTEST function example returns the probability associated with the Student's paired t-test with a one-tailed distribution for the two arrays of data A1 and B1. This type of test is used to compare the means of two paired sets of data, to determine if the difference between them is statistically significant.

• `=TTEST( A1:A12, B1:B12, 2, 1 )`

The TTEST function example returns the probability associated with the Student's paired t-test with a two-tailed distribution for the two arrays of data A1 and B1. This type of test is used to determine if the difference between two paired sets of data is statistically significant.

• `=TTEST( A1:A12, B1:B12, C1:C12, 2, 1 )`

The TTEST function can also be used to compare the means of three or more paired sets of data, by adding additional arguments to the function. For example, this will return the probability associated with the Student's paired t-test with a two-tailed distribution for the three arrays of data A1, B1, and C1.

## Summary

The TTEST function is used to determine whether two sets of data are likely to have come from the same population. It returns the probability of observing the difference between the means of the two data sets by chance.

• The TTEST function is still available in Excel 2010, but not in future versions. It has been replaced by the T.Test function.