Microsoft KB Archive/173923

= TDIST Function Returns #NUM! If X Argument Is Negative =

Article ID: 173923

Article Last Modified on 8/17/2005

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APPLIES TO


 * Microsoft Excel 97 Standard Edition
 * Microsoft Excel 95 Standard Edition
 * Microsoft Excel 5.0 Standard Edition
 * Microsoft Excel 98 for Macintosh
 * Microsoft Excel 95a
 * Microsoft Excel 4.0 Standard Edition
 * Microsoft Excel 4.0a
 * Microsoft Excel 5.0c
 * Microsoft Excel 5.0 Standard Edition
 * Microsoft Excel 4.0 for Macintosh
 * Microsoft Excel 5.0 for Macintosh
 * Microsoft Excel 5.0a for Macintosh

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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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