CHIDIST function
Returns the righttailed probability of the chisquared distribution. The χ2 distribution is associated with a χ2 test. Use the χ2 test to compare observed and expected values. For example, a genetic experiment might hypothesize that the next generation of plants will exhibit a certain set of colors. By comparing the observed results with the expected ones, you can decide whether your original hypothesis is valid.
Important This function has been replaced with one or more new functions that may provide improved accuracy and whose names better reflect their usage. This function is still available for compatibility with earlier versions of Excel. However, if backward compatibility is not required, you should consider using the new functions from now on, because they more accurately describe their functionality.
For more information about the new functions, see CHISQ.DIST function and CHISQ.DIST.RT function.
Syntax
CHIDIST(x,deg_freedom)
The CHIDIST function syntax has the following arguments:

X Required. The value at which you want to evaluate the distribution.

Deg_freedom Required. The number of degrees of freedom.
Remarks

If either argument is nonnumeric, CHIDIST returns the #VALUE! error value.

If x is negative, CHIDIST returns the #NUM! error value.

If deg_freedom is not an integer, it is truncated.

If deg_freedom < 1 or deg_freedom > 10^10, CHIDIST returns the #NUM! error value.

CHIDIST is calculated as CHIDIST = P(X>x), where X is a χ2 random variable.
Example
The example may be easier to understand if you copy it to a blank worksheet.
How do I copy an example?

Select the example in this article.
Important Do not select the row or column headers.
Selecting an example from Help

Press CTRL+C.

In Excel, create a blank workbook or worksheet.

In the worksheet, select cell A1, and press CTRL+V.
Important For the example to work properly, you must paste it into cell A1 of the worksheet.

To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.
After you copy the example to a blank worksheet, you can adapt it to suit your needs.

