DAX Function Guide

This function will calculate the two-tailed Student’s T-Distribution. The Student’s T-Distribution is a continuous probability distribution that is frequently used for testing hypotheses on small sample data sets.

• If either argument is nonnumeric, T.INV.2T returns the #VALUE! error value.
• If probability <= 0 or if probability > 1, T.INV.2T returns the #NUM! error value.
• If deg_freedom is not an integer, it is truncated.
• If deg_freedom < 1, T.INV.2T returns the #NUM! error value.
• T.INV.2T returns that value t, such that P(|X| > t) = probability where X is a random variable that follows the t-distribution and P(|X| > t) = P(X < -t or X > t).
• A one-tailed t-value can be returned by replacing probability with 2*probability. For a probability of 0.05 and degrees of freedom of 10, the two-tailed value is calculated with T.INV.2T(0.05,10), which returns 2.28139. The one-tailed value for the same probability and degrees of freedom can be calculated with T.INV.2T(2*0.05,10), which returns 1.812462.Given a value for probability, T.INV.2T seeks that value x such that T.DIST.2T(x, deg_freedom, 2) = probability. Thus, precision of T.INV.2T depends on precision of T.DIST.2T.