CHIDIST Function (Gnumeric)

• Introduced: Gnumeric 0.25, explicitly listed among the new functions in its release notes.
• Availability: Supported in Gnumeric 1.12.62 according to its function-specific registration. No retirement endpoint is established.
• Scope: Desktop Gnumeric with the fn-stat module enabled. Examples use English comma-separated formulas.
• Checked: October 14, 2026. Reference and boundary tables were recalculated by Gnumeric 1.12.57 and checked independently. The 1.12.62 contract was source-checked, not executed.

For positive x and degrees of freedom ν, the survival probability is the regularized upper gamma function Q(ν/2,x/2). At ν=2 it simplifies to exp(−x/2). The function supplies a distribution tail; choosing appropriate degrees of freedom is part of the statistical model. Official CHIDIST reference.

=CHIDIST(x,dof)

All arguments shown are required. Use numeric cells or numeric inputs. The formulas use decimal points and commas; localized entry conventions require separate checks. Gnumeric 1.12.62 help and evaluator.

Enter each formula in a separate cell. The displayed references are rounded to twelve decimal places and agree with the recorded Gnumeric 1.12.57 recalculation within ordinary floating-point precision. Keep the stored result for subsequent calculations.

Put statistic 5.3 in A2 and degrees of freedom 2 in B2. =CHIDIST(A2,B2) gives approximately 0.070651213060. Under an appropriate chi-squared reference distribution, that is an upper-tail probability of about 7.07%.

Do not label it “probability below 5.3.” That left-tail value would be =1-CHIDIST(A2,B2). A small upper-tail value indicates a large statistic relative to the chosen reference distribution, not by itself proof of a particular real-world explanation.

Reconstruct a simple goodness-of-fit statistic

Suppose observed category counts are 18,22,20 and expected counts are 20,20,20. Enter observations in A5:A7 and expectations in B5:B7. In C5 use =(A5-B5)^2/B5 and fill down. =SUM(C5:C7) is 0.4.

If the three-category model is fully specified without fitted parameters, the usual degrees of freedom are 2. =CHIDIST(0.4,2) is approximately 0.818730753078. Estimated parameters or unsuitable expected counts change the test requirements; this arithmetic example is not a universal goodness-of-fit recipe.

Unlike FDIST’s wrapper, CHIDIST does not reject negative x. Its distribution helper returns survival probability 1 for negative thresholds; CHIDIST(-1,2) was observed as 1 in 1.12.57. This is a support-boundary convention, not permission to use a negative sum-of-squares statistic. Degrees of freedom are floored, and values below 1 after flooring return #NUM!.

The following are observed cell results from the same 1.12.57 command-line recalculation. F5 was genuinely empty. A blank is not necessarily an omitted argument or a valid observation, so validate required data instead of treating every defaulted zero as intentional.

The fixtures do not certify every locale, extreme tail, imported type or newer binary build. The current wrapper agrees with the documented argument contract; shared numerical helpers can change between releases.

• CHIINV
• CHITEST
• CHIDIST official manual entry
• Version-pinned argument contract and calculation