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# WorksheetFunction.T_Test Method (Excel)

Office 2013

Published: July 16, 2012

Returns the probability associated with a Student 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.

expression .T_Test(Arg1, Arg2, Arg3, Arg4)

expression A variable that represents a WorksheetFunction object.

### Parameters

Name

Required/Optional

Data Type

Description

Arg1

Required

Variant

Array1 - The first data set.

Arg2

Required

Variant

Array2 - The second data set.

Arg3

Required

Double

Tails - 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.

Arg4

Required

Double

Type - The kind of t-Test to perform.

### Return Value

Double

If type equals

This test is performed

1

Paired

2

Two-sample equal variance (homoscedastic)

3

Two-sample unequal variance (heteroscedastic)

• 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 non-numeric, 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.