T test function

Returns the probability associated with a Student's t-Test. Use T.TEST to determine whether two samples are likely to have come from the same two underlying populations that have the same mean.

Syntax

T.TEST(array1,array2,tails,type)

The T.TEST function syntax has the following arguments:

• Array1     Required. The first data set.

• Array2     Required. The second data set.

• Tails     Required. 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.

• Type     Required. The kind of t-Test to perform.

Parameters

If type equals	This test is performed
1	Paired
2	Two-sample equal variance (homoscedastic)
3	Two-sample unequal variance (heteroscedastic)

Remarks

• If array1 and array2 have a different number of data points, and type = 1 (paired), T.TEST returns the #N/A error value.

• The tails and type arguments are truncated to integers.

• If tails or type is nonnumeric, T.TEST returns the #VALUE! error value.

• If tails is any value other than 1 or 2, T.TEST returns the #NUM! error value.

• T.TEST uses the data in array1 and array2 to compute a non-negative t-statistic. If tails=1, T.TEST returns the probability of a higher value of the t-statistic under the assumption that array1 and array2 are samples from populations with the same mean. The value returned by T.TEST when tails=2 is double that returned when tails=1 and corresponds to the probability of a higher absolute value of the t-statistic under the "same population means" assumption.

Example

Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.

Data 1	Data 2
3	6
4	19
5	3
8	2
9	14
1	4
2	5
4	17
5	1
Formula	Description	Result
=T.TEST(A2:A10,B2:B10,2,1)	Probability associated with a Student's paired t-Test, with a two-tailed distribution.	0.196016