I measured one dependent variable between three groups of data (control, group1, group2).The result of ttest 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?
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If you've got more than two groups, don't use ttests (due to the multiple comparisons trap). Use a oneway ANOVA instead (based on an Ftest). Then if you want a posthoc test after that, use Tukey's HSD. 

