I measured one dependent variable between three groups of data (control, group1, group2).The result of t-test indicates significant difference between control and group 1 (p vale =.04), control and group 2(p value .01), but not significant between group 2 and group 3.Do I still need to use the post hoc test? If so, which test is the most appropriate?
If you've got more than two groups, don't use t-tests (due to the multiple comparisons trap). Use a one-way ANOVA instead (based on an F-test). Then if you want a post-hoc test after that, use Tukey's HSD.