# WorksheetFunction.T_Inv_2T (Excel)

Returns the t-value of the Student t-distribution as a function of the probability and the degrees of freedom.

If either argument is non-numeric, T_Inv_2T returns the #VALUE! error value. If probability < 0 or if probability > 1, T_Inv_2T returns the #NUM! error value. If degrees_freedom is not an integer, it is truncated. If degrees_freedom < 1, T_Inv_2T returns the #NUM! error value. T_Inv_2T returns the 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_RT(x, degrees_freedom, 2) = probability. Thus, precision of T_Inv_2T depends on precision of T_Dist_RT. T_Inv_2T uses an iterative search technique. If the search has not converged after 100 iterations, the function returns the #N/A error value.

**T_Inv_2T** (Arg1, Arg2)

```
Dim dblArg1 As Double: dblArg1 =
Dim dblArg2 As Double: dblArg2 =
Dim dblT_Inv_2T As Double
dblT_Inv_2T = WorksheetFunction.T_Inv_2T(Arg1:=dblArg1, Arg2:=dblArg2)
```

## Arguments

Arg1, Arg2Arg1 (Double) - Probability - The probability associated with the two-tailed Student t-distribution.

Arg2 (Double) - Degrees_freedom - The number of degrees of freedom with which to characterize the distribution.