Ch. 8

Flow chart

Between groups designs

Within groups designs

Completely randomized designs

1.Randomize groups

2. Manipulate

3. Compare data

• Statistic of Choice: T-test

Multilevel Completely Randomized Design

1. Randomize groups

2. Manipulate

3. Compare data

• Statistic of Choice: Anova



• Null hypothesis







• Post hoc tests







• A priori tests

Factorial designs=more than 2 independent variables

• 3 Null hypotheses



• Main Effect A





• Main Effect B





• Interaction Effect

Eight possible outcomes for a 2x2 design.

1. Non significant effects

2. Significant effect for A only

3. Significant effect for B only

4. Significant interaction alone

5. Interaction and Main effect for A significant

6. Interaction and Main effect for B significant

7. Main effects only significant

8. All effects significant