Question

Week 8 Discussion

Consider the different post hoc tests discussed in the readings and respond to the following:

Describe the general rationale behind using post hoc tests (i.e., when they are used and why).

One of the advantages of using an ANOVA (compared to using t-tests) is also a disadvantage—using an ANOVA makes it necessary to use post hoc tests if there is a significant main effect. We use a post hoc test because there is one specific advantage in using an ANOVA. Explain why using an ANOVA naturally leads to the need to have post hoc tests (hint: consider what you are examining when you conduct a post hoc analysis).

Conducting a post hoc test is similar to conducting multiple t-tests. As a result, it would seem natural to want to bypass the ANOVA and just use repeated t-tests. Explain why this approach is not necessarily a good idea and why an ANOVA followed by a post hoc analysis is beneficial.

Describe an experimental hypothesis and explain which post hoc test you would use if you find a significant overall effect. Include in your explanation the pros and cons of each test in making your decision.

Answer 1

ANOVA is used to test whether the means of more than two groups are significantly different.

When we observe a significant difference in the groups, we use post hoc test.

The post hoc tests the pair wise comparison and let us know between which groups, the significant difference occurs.

The three main Post-Hoc tests are:

(i) LSD test.

(ii) Tukey’s HSD test.

(iii) Scheffe’s test.

Multiple t-tests would consume much time. However, ANOVA will compares together easily in one step and Pos-Hoc would help us to find the difference in the group.