The T.INV.2T function returns the two-tailed inverse of the Student’s t-distribution
The T.INV.2T function syntax has the following arguments:
- Probability (required argument) – This is the probability associated with the Student’s T Distribution. It should be between 0 and 1.
- Deg_freedom (required argument) – The number of degrees of freedom with which to characterize the distribution.
Example: Let’s look at some Excel T.INV.2T function examples and explore how to use the T.INV.2T function as a worksheet function in Microsoft Excel:
Suppose we are given the following data:
If we want to calculate the value of the function for a probability of 0.2, the formula to use will be:
So, the T-value of the Student’s T-distribution for the data above is 1.475884049
- 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.