# t-Test Assuming Unequal Variance Returns Incorrect DF Value

Last reviewed: September 12, 1996
Article ID: Q102818
The information in this article applies to:

- Microsoft Excel for Windows, versions 4.0, 4.0a

## SYMPTOMS

In Microsoft Excel, when you use the Analysis ToolPak t-Test: Two-Sample Assuming Unequal Variances function or tool, the degree of freedom (df) that is returned is incorrect.

Degree of freedom should be a whole number. The two-sample assuming unequal variances returns a decimal (real) number.

## STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. This problem has been corrected in Microsoft Excel version 5.0.

## MORE INFORMATION

The t-Test: Two-Sample Assuming Unequal Variances tool performs a two-sample student's t-test. This form of the test assumes that the variances of both ranges of data are unequal and is referred to as a heteroscedastic t-test.

### When to use a t-test

Use a t-test to determine whether two sample means are equal. Use this test when the groups under study are distinct. Use a paired test when there is one group before and after a treatment.

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> Additional reference words: 4.00 4.00a ttest pttestv atp pack integer

Last reviewed: September 12, 1996
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