Description Computes the student's T-distribution from the data in two specified arrays, then computes the probability.
Syntax TTEST (array1, array2, tails, type)
| Argument | Description | |
|---|---|---|
| array1 and array2 | Two range references or an array constants containing numeric values. Text, logical values, and empty cells are ignored. Array1 and array2 must contain the same potential number of values. | |
| tails | Enter 1 for a one-tailed distribution, 2 for two-tailed. | |
| type | The type of T-test you want to perform on the given arrays. The options are: | |
| 1 | Paired values | |
| 2 | Two distributions with the same variance | |
| 3 | Two distributions with different variances | |
Remarks In type option 1, aggregate values for mean, variance, and counts are determined for both arrays. In options 2 and 3, those values are determined for each array independently.
TTEST uses TDIST to compute the T-distribution. TDIST requires that its degrees of freedom argument be an integer. However, in type option 3, the computed degrees of freedom will usually not be an integer. Therefore, in this case, the function uses the incomplete beta function instead of TDIST.
Equation The equations used in this function can be found on pages 616-618 of Numerical Recipes in C: The Art of Scientific Computing, 2nd ed., William Press, Saul A. Teukolsky, William T. Vetterling, Brian P. Flannery, Cambridge University Press, 1992.
Examples This function returns 0.77:
See Also CHITEST, FTEST, ZTEST
