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WorksheetFunction.T_Inv_2T Method (Excel)

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

Version Added: Excel 2010

expression .T_Inv_2T(Arg1, Arg2)

expression A variable that represents a WorksheetFunction object.




Data Type





Probability - The probability associated with the two-tailed Student t-distribution.




Degrees_freedom - The number of degrees of freedom with which to characterize the distribution.

Return Value


  • 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 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_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.

    Note Note

    In some tables, probability is described as (1-p).