In an ANOVA with a between-groups (Treatment) population variance estimate of 30 and a within-groups (Error) estimate of 25, the F ratio is A) 25 / (30-25) = 5.00 B) (30-25) / 30 = 0.17 C) 25 / 30 = 0.83 D) 30 / 25 = 1.20 The overall test of the significance of the difference among groups in an ANOVA is called A) an omnibus test. B) a planned comparison. C) an absolute contrast. D) a post-hoc test