How to Find an F Critical Value with F.INV.RT in Excel

Use F.INV.RT to find the F cut-off for an ANOVA or a two-tailed variance test in a field trial.

You will learn to

• Find the ANOVA critical F
• Find the upper critical F for a two-tailed variance test
• Find the lower critical F

How it works

F.INV.RT returns the F value with a chosen probability to its right — the critical value an F statistic must exceed to be significant. For a one-way ANOVA with 4 treatments and 24 plots, =F.INV.RT(5%,3,20) returns about 3.098.

For a two-tailed test of two variances, split alpha between the tails: the upper cut-off is F.INV.RT(alpha/2,df1,df2) and the lower cut-off is F.INV.RT(1-alpha/2,df1,df2). A ratio outside those two values means the spreads differ.

=F.INV.RT(0.05,3,20)