CRITBINOM Function (Gnumeric)

• Introduced: First release not established; this name is present in the tested Gnumeric 1.12.57 and the cited 1.12.62 source.
• 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.

The defining inequality is P(X≤k−1)<alpha≤P(X≤k), for an interior target probability. Because the binomial distribution is discrete, the cumulative probability usually jumps past the target rather than equaling it exactly. Official CRITBINOM reference.

=CRITBINOM(trials,p,alpha)

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 trials 10 in A2, success probability 0.5 in B2 and target cumulative probability 0.75 in C2. =CRITBINOM(A2,B2,C2) returns 6.

Check the neighboring counts: =BINOMDIST(5,10,0.5,TRUE()) is 0.623046875, below 0.75, while =BINOMDIST(6,10,0.5,TRUE()) is 0.828125, at or above 0.75. This pair of inequalities is stronger evidence for the discrete quantile than expecting a round trip to equal 0.75.

Translate an upper-tail threshold carefully

To find a count whose exceedance probability is no more than 5%, supply alpha=0.95: =CRITBINOM(10,0.5,0.95) returns 8. Here P(X>8)=0.0107421875, while P(X≥8)=0.0546875. A rule using “greater than 8” therefore differs from “at least 8.”

Choose the intended event before deriving a rejection or capacity rule. The jump in the distribution prevents an exact 5% tail in this example; the function does not interpolate a fractional success count to manufacture one.

Tail-label warning: the short Gnumeric help calls this a right-tailed critical value and labels alpha as an area of the tail. The pinned evaluator actually passes alpha to qbinom with lower_tail=TRUE. The native neighboring-CDF check above confirms the left-tail quantile interpretation. For an upper-tail budget q, use alpha=1−q and then check the strict versus inclusive event. The wrapper floors trials, permits alpha endpoints, and rejects probabilities outside [0,1].

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.

• BINOMDIST
• CRITBINOM official manual entry
• Version-pinned argument contract and calculation