The omnibus null hypothesis when performing an analysis of variance is there are differences between group means, however, no prediction is made concerning where the differences lie.

False, the omnibus null is that all group means are the same.
false
True
true
False
Unlike t-tests an ANOVA may be used to test for differences among more than 2 groups.

True, An analysis of variance (ANOVA) is most often used to determine if there are differences among 3 or more group means. However, if there are more than 2 groups an ANOVA does not provide information regarding where the differences lie.
true
True
false
False
Unlike t-tests, an ANOVA uses both differences between group means and differences within groups to determine whether the difference are significant.

False, both t-tests and ANOVAs use both. In a t test the difference between means is in the numerator. In an ANOVA, the variance of the grouop means (multiplied by n) is in the numerator.
false
True
true
False
It is valid to do the Tukey HSD test without first finding a signficant effect with an ANOVA.

True, the Tukey HSD controls the Type I error rate and is valid without first running an ANOVA.
true
True
false
False