CHISQ.INV in WPS Spreadsheet: Find a Chi-Square Left-Tail Quantile

=CHISQ.INV(0.95,2) has an independent expected result of 5.991464547108. This threshold has 95% of a chi-square distribution with 2 degrees of freedom below it, leaving 5% above it. The result is a statistic value, not a probability.

CHISQ.INV(probability,deg_freedom)

Both arguments are required numeric inputs. probability is the left cumulative probability. Use a value strictly between 0 and 1 for the examples here, such as 0.95 or 95%, not 95. deg_freedom specifies the distribution. The WPS lesson says fractional values are truncated; choose a positive integer deliberately rather than relying on truncation.

Enter 0.95 in B2 and 2 in B3. Label them Left probability and Degrees of freedom. Enter =CHISQ.INV(B2,B3) in D2. Expect approximately 5.991464547108 under the documented model.

With 2 degrees of freedom, F(x)=1−exp(−x/2). Solving F(x)=p gives x=−2 ln(1−p). Thus −2 ln(0.05) is an independent calculation of the same threshold. This mathematical control does not establish WPS’s last-digit precision.

At p=0.5 and df=2, expect 1.386294361120. At p=0.05, expect 0.102586588775. Increasing the left probability increases the quantile. If you wanted a 5% upper-tail cutoff, use a left probability of 0.95, not 0.05.

CHIINV is documented as a right-tail inverse, so transferring its probability unchanged into CHISQ.INV changes the question. Do not infer that similarly named inverse functions are aliases.

The central 90% interval puts 5% in each tail:

=CHISQ.INV(0.05,2)
=CHISQ.INV(0.95,2)

The independently expected endpoints are 0.102586588775 and 5.991464547108. Chi-square distributions are asymmetric; averaging these bounds is not a way to recover the mean. These are distribution quantiles, not automatically confidence limits for an observed dataset. A confidence interval for a variance would require a separate derivation and justified assumptions.

The lesson documents #VALUE! for nonnumeric inputs and truncation of fractional df. Its probability-error paragraph mistakenly names CHISQ.INV.RT; its title, definition and walkthrough consistently specify a left-tail inverse. This guide uses that consistent left-tail contract and does not transfer the typo’s name or infer endpoint behavior from it.

The source also disagrees internally on whether the maximum df endpoint is included. Small positive integer df and strict interior probabilities avoid both unresolved boundaries. Introduction, retirement and precise implementation limits are not established. A result very far into a tail is especially sensitive to input rounding; keep probability cells at full precision.

The official WPS CHISQ.INV lesson was checked on October 19, 2026. The captured source does not establish a specific edition or numeric build. This Chinese first-party documentation is not proof of universal English-global, Mac, Linux, web or mobile support. Introduction and retirement versions remain unknown. All numerical results in this guide are independently calculated expectations, not native WPS test results or borrowed Excel outputs. Current GUI access was unavailable; no current-application screenshots or native execution are claimed.

CHIINV, CHIDIST. Browse the WPS function library.