one tail (1): Returns the value for a one-tailed distribution.
two tails (2): Returns the value for a two-tailed distribution.
test-type: A modal value specifying the type of t-test to perform.
paired (1): Perform a paired test.
two-sample equal (2): Perform a two-sample equal variance (homoscedastic) test.
two-sample unequal (3): Perform a two-sample unequal variance (heteroscedastic) test.
Examples
Suppose that cells B2 through G2 contain the values 57, 75, 66, 98, 92, and 80, respectively, and represent the sample-1-values. Suppose that cells B3 through G3 contain the values 87, 65, 45, 95, 88, and 79, respectively, and represent the sample-2-values. The various TTEST values for these two samples can be found with the formulas:
=TTEST(B2:G2, B3:G3, 1, 1) returns 0.418946725989974, for the one-tailed, paired test.
=TTEST(B2:G2 ,B3:G3, 2, 1) returns 0.837893451979947 for the two-tailed, paired test.
=TTEST(B2:G2, B3:G3, 1, 2) returns 0.440983897602811 for the one-tailed, two-sample equal test.
=TTEST(B2:G2, B3:G3, 2, 2) returns 0.881967795205622 for the two-tailed, two-sample equal test.
=TTEST(B2:G2, B3:G3, 1, 3) returns 0.441031763311189 for the one-tailed, two-sample unequal test.