FTEST Function (LibreOffice Calc)

• Introduced: First release not established. The LibreOffice 3.3 function appendix documents this name; that establishes historical presence, not its introduction.
• Supported in: LibreOffice 26.8.1.1; no final supported release established.
• Scope: Desktop Calc. Examples use English function names and semicolon argument separators; the numeric contract is release-specific.
• Checked: October 14, 2026. Retained official sources and independent mathematics checked. No new LibreOffice Calc execution is claimed here.

FTEST compares the sample variances of two independent normal populations. It computes variances from the observations, rather than accepting two precomputed variance cells. The classical F reference is sensitive to departures from normality; it is not a general-purpose guarantee about arbitrary distributions. Pinned implementation.

A p-value summarizes compatibility with equal population variances under that sampling model. It is not the probability that the populations are identical. Different means can coexist with equal variances, and a non-small p-value is not proof of equality.

=FTEST(Data1; Data2)

Exactly two arguments are required. Each sample needs at least two numeric observations and a nonzero sample variance. The ranges may have different sizes. LibreOffice Help explicitly excludes text and empty cells in ranges; use COUNT to verify the included numeric observations. Zero is a valid observation and is not a missing-data marker.

The evaluator places the larger sample variance in the numerator and carries that sample’s n−1 degrees of freedom with it. It then returns twice the smaller F-distribution tail, so exchanging the ranges preserves the mathematical result.

Enter the following data. D has only three observations; keep D5 empty and exclude it explicitly in the formulas.

These are independently computed values from the cited release expression, rounded to twelve decimal places. They are ordinary mathematical reference p-values.

For A and B, VAR gives 1.666666666667 and 6.666666666667, respectively. The selected ratio is 4 with df1=df2=3. Keep the original observations: entering only those two variance cells would leave each FTEST sample with a single observation.

C contains 1, 1, 1, 3 and D contains 1, 2, 3. Both sample variances are exactly 1. LibreOffice returns approximately 0.929516003090 in either order.

To calculate a conventional doubled-smaller-tail result explicitly, put the fixed-order variance ratio in F2 with =VAR(D2:D4)/VAR(C2:C5), then put its upper tail in F3 with =FDIST(F2;COUNT(D2:D4)-1;COUNT(C2:C5)-1). =2*MIN(F3;1-F3) gives approximately 0.929516003090. Both sample variances must be positive.

The explicit calculation is useful for checking orientation and degrees of freedom when porting a workbook. Do not choose between a one-sided and two-sided scientific alternative after inspecting the data.

Before using the result, inspect outliers and data-entry problems without automatically deleting observations. Keep measurement units consistent: multiplying just one sample by a conversion factor changes its variance by the square of that factor. Errors from insufficient data or constant samples should remain visible rather than be replaced with zero.

• Function-specific LibreOffice 26.8.1.1 implementation
• Official FTEST Help

The numerical references were recomputed independently against the retained release contract. Native application execution, import paths and locale behavior are not newly verified by these reference calculations.