TTEST function returns the probability of a Student's t-Test.
@array1 is the first data set and @array2 is the second data set. If @tails is one, TTEST uses the one-tailed distribution and if @tails is two, TTEST uses the two-tailed distribution. @type determines the kind of the test:
1 Paired test
2 Two-sample equal variance
3 Two-sample unequal variance
If the data sets contain a different number of data points and the test is paired (@type one), TTEST returns the #N/A error. @tails and @type are truncated to integers. If @tails is not one or two, TTEST returns #NUM! error. If @type is any other than one, two, or three, TTEST returns #NUM! error.