Knowledge Base

TDIST Function Returns #NUM! If X Argument Is Negative

Article ID: 173923

Article Last Modified on 8/17/2005

APPLIES TO

This article was previously published under Q173923

SYMPTOMS

In Microsoft Excel, if you enter a formula that uses the TDIST function, the formula may return a #NUM! error. This behavior may occur even when you use a value greater than or equal to 1 for the Degrees_Freedom argument and a value of 1 or 2 for the Tails argument.

CAUSE

This behavior occurs if the X argument is negative (less than zero) in the following syntax 
   TDIST(x,degrees_freedom,tails)
where X is the numeric value at which to evaluate the distribution. For example, the following formula 
   =TDIST(-1.96,60,2)
returns a #NUM! error because the X argument is negative.

This behavior is by design of Microsoft Excel.

RESOLUTION

To resolve this problem, use a value that is greater than or equal to zero for the X argument in the TDIST function.

MORE INFORMATION

In Microsoft Excel, the TDIST function allows you to calculate the Student's t-distribution. The t-distribution is used in the hypothesis testing of small sample data sets. You can use the TDIST function in place of a table of critical values for the t-distribution.

The "Function Reference" for Microsoft Excel 4.x and the Microsoft Excel Help file for other versions of Microsoft Excel include the following information about the TDIST function:

  • If any argument is nonnumeric, the TDIST function returns a #VALUE! error.
  • The Degrees_Freedom and Tails arguments are truncated to integers.
  • If Degrees_Freedom is less than 1, the TDIST function returns a #NUM! error.
  • If Tails has a value other than 1 or 2, the TDIST function returns a #NUM! error.
The "Function Reference" and Help files do not mention any restrictions for the X argument. However, the following additional information applies:

If X is less than 0, the TDIST function returns a #NUM! error.


Additional query words: XL98 XL97 XL7 XL5 XL4 XL

Keywords: kbprb KB173923


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