TTestType
Specifies the design of the t-test for power analysis calculations.
The test type determines how sample size [n] is interpreted and how the noncentrality parameter is computed. For TWO_SAMPLE, [n] is the per-group sample size and the noncentrality scales by the square root of n/2. For ONE_SAMPLE and PAIRED, [n] is the total sample size (or number of pairs) and the noncentrality scales by the square root of n.