Work out f distribution instantly with clear inputs, formula shown and shareable results.
The F distribution is the ratio of two scaled chi-square variables, so it is the natural reference for comparing variances and for ANOVA. It is right-skewed and depends on two separate degrees of freedom.
F CDF
P(F ≤ f) = I_(d₁f/(d₁f + d₂))(d₁/2, d₂/2)
The right-tail p is about 0.0497, just under the 5% critical value of 3.4903.
One for each variance estimate in the ratio; swapping them inverts the F value and its critical points.