Updated: 31 July 2015

Use T_INV to calculate the inverse of the left-tailed cumulative probability distribution of Student's t-distribution.

SELECT [wct].[T_INV](

<@Probability, float,>

,<@Degrees_freedom, float,>)

the probability to be evaluated. *@Probability* must be of a type **float** or of type that intrinsically converts to **float**.

the number of degrees of freedom. *@df *must of a type **float** or of a type that intrinsically converts to **float**.

float

· 0 < *@df*

· 0 < *@Probability* < 1

· If *@Probability* = 0.5 then zero is returned

In this example we calculate the value at 0.95 with 12 degrees of freedom.

SELECT

wct.T_INV(

0.95 --@Probability

,12 --@Degrees_freedom

) as T_INV

This produces the following result