# CHIINV function

Returns the inverse of the one-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.

Syntax

CHIINV(probability,degrees_freedom)

Probability     is a probability associated with the chi-squared distribution.

Degrees_freedom     is 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 degrees_freedom is not an integer, it is truncated.
• If degrees_freedom < 1 or degrees_freedom > 10^10, CHIINV returns the #NUM! error value.

Given a value for probability, CHIINV seeks that value x such that CHIDIST(x, degrees_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

The example may be easier to understand if you copy it to a blank worksheet.

• Create a blank workbook or worksheet.
• Select the example in the Help topic.

Note   Do not select the row or column headers.

Selecting an example from Help
• Press CTRL+C.
• In the worksheet, select cell A1, and press CTRL+V.
• 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.
A B
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 (18.3069735)

Applies to:
Excel 2007