Question

Which post-hoc test is best to use if you want to compare all groups to a control? Why is this a preferable option?

a. Tukey's HSD
b. Bonferroni
c. Scheffé's test
d. Fisher's LSD

Answer 1

Tukey's HSD is the best post-hoc test to compare all groups to a control. It adjusts for multiple comparisons and allows control of the overall Type I error rate.

Step-by-step explanation:

The post-hoc test that is best to use if you want to compare all groups to a control is Tukey's HSD. This is a preferable option because Tukey's HSD adjusts for multiple comparisons, allowing you to control the overall Type I error rate when making pairwise comparisons.

To use Tukey's HSD:

1. Perform an ANOVA to test for differences between groups.
2. If the ANOVA is significant, use Tukey's HSD to compare all groups to the control group.
3. Calculate the test statistic, which follows a studentized range distribution.
4. Find the p-value associated with the test statistic.
5. Compare the p-value to a pre-determined significance level (e.g., 0.05).