# CHIINV function

Returns the inverse of the right-tailed probability of the chi-squared distribution. If probability = CHIDIST(x,...), then CHIINV(probability,...) = x. Use this function to compare observed results with expected ones in order to 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. Although this function is still available for backward compatibility, you should consider using the new functions from now on, because this function may not be available in future versions of Excel.

## Syntax

CHIINV(probability,deg_freedom)

The CHIINV function syntax has the following arguments:

• Probability     Required. A probability associated with the chi-squared distribution.

• Deg_freedom     Required. The number of degrees of freedom.

## Remarks

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

• If probability < 0 or probability > 1, CHIINV returns the #NUM! error value.

• If deg_freedom is not an integer, it is truncated.

• If deg_freedom < 1, CHIINV returns the #NUM! error value.

Given a value for probability, CHIINV seeks that value x such that CHIDIST(x, deg_freedom) = probability. Thus, precision of CHIINV depends on precision of CHIDIST. CHIINV uses an iterative search technique. If the search has not converged after 100 iterations, the function returns the #N/A error value.

## Example

Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.

 Data Description 0.050001 Probability associated with the chi-squared distribution 10 Degrees of freedom Formula Description Result =CHIINV(A2,A3) Inverse of the one-tailed probability of the chi-squared distribution. 18.306973 