# T.TEST

### Definition

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.

### Sample Usage

### 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.

### In order to use the T.TEST formula, start with your edited Excellentable:

### Then type in the T.TEST formula in the area you would like to display the outcome:

### By adding the values you would like to calculate the T.TEST formula for, Excellentable will generate the outcome: