The Excel TTEST 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.
Syntax: TTEST( array1, array2, tails, type )
|array1||–||The first data set|
|array2||–||The second data set (must have the same length as array1)|
|tails||–||The number of tails for the distribution. This must be either :
|type||–||An integer that represents the type of t-test. This can be either :
Ttest Function Examples
Columns A and B of the 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 Ttest 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 by :
This gives the result 0.898141379, which is double the probability associated with the one-tailed test.
If you get an error from the Excel TTEST Function, this is likely to be one of the following :
|#N/A||–||Occurs if the two supplied arrays have different lengths|
|#NUM!||–||Occurs if either the supplied tails argument has any value other than 1 or 2 the supplied type argument is not equal to 1, 2 or 3|
|#VALUE!||–||Occurs if either the tails argument or the type argument is non-numeric|