The Excel T.DIST.RT Function

Related Function:
T.DIST.2T Function
T.DIST.RT and TDIST functions

The TDIST.RT function is new to Excel 2010. This function (along with the new Excel 2010 T.DIST.2T function), replaces the old TDIST function, that is available in earlier versions of Excel.

The T.DIST.RT function also has the advantage that, unlike the TDIST function, it can accept negative values of x. Therefore, if possible, you should use this function in preference to the TDIST function.

Function Description

The Excel T.DIST.RT function calculates the right-tailed Student's T Distribution, which is a continuous probability distribution that is frequently used for testing hypotheses on small sample data sets.

The syntax of the function is:

T.DIST.RT( x, degrees_freedom )

where the function arguments are:

x - The value at which you want to evaluate the right-tailed Student's T-Distribution.
degrees_freedom - The number of degrees of freedom (must be ≥ 1).

T.Dist.Rt Function Example

Plot of 1-Tailed Student's T Distribution with 10 Degrees of Freedom
Right-Tailed Student's T-Distribution with 10 Degrees of Freedom

The above chart on the right shows the right-tailed Student's T Distribution with 10 degrees of freedom.

If you want to calculate the value of this function at x = 1, this can be done using the Excel T.Dist.Rt function, as follows:

=T.DIST.RT( 1, 10 )

This gives the result 0.170446566, or 17.04%.

Similarly, if you want to calculate the value of the function, at x = -1, this can be done as follows:

=T.DIST.RT( -1, 10 )

This gives the result 0.829553434, or 82.96%.

For further information and examples of the Excel T.Dist.Rt function, see the Microsoft Office website.

T.Dist.Rt Function Errors

If you get an error from the Excel T.Dist.Rt function this is likely to be one of the following:

Common Errors
#NUM! - Occurs if the supplied degrees_freedom argument is < 1.
#VALUE! - Occurs if one or both of the supplied arguments are non-numeric.