1. Explain2 the advantages of using a multiple group experiment, rather than several simple experiments, to compare the effectiveness of three or more different treatments.
2. Explain2 why a researcher examining the effects of two different treatments might want to include a no-treatment control group.
3. Explain2 why using three or more different levels of treatment allows you to explore the functional relationship between the treatment variable and the outcome variable. Then, explain2 why you would want to explore the functional relationship between two variables.
4. Explain2 why multiple-group experiments may have better construct validity than simple experiments. In your answer, be sure to address hypothesis-guessing, empty control groups, and confounding variables.
5. Rank6 the following experiments on the effects of exercise and mood in terms of how much construct validity you think each would have. Justify6 your rankings.
a. A 30 min of exercise group and two control groups: a group that watched music videos and a group that took an acting class.
b. Two levels of exercise (0 min, 30min)
6. Rank6the following experiments on the effects of exercise and mood in terms of how much construct validity you think each would have. Justify6 your rankings.
a. Three levels of exercise (0 min, 15 min, and 30 min)
b. Two levels of exercise (0 min, 30 min)
c. Four levels of exercise (0 min, 15 min, 30 min, and 45 min)
d. Four levels of exercise (15 min, 30 min, 45 min, and 60 min)
7. Define1 within-group variability. Define1 between-group variability. Compare4 and contrast4 within-groups variability and between-groups variability.
8. Explain2 why, all other things being equal, the greater the variability between group means, the greater the chance that the treatment had an effect.
9. Defend4 using the term "error variance" instead of "within-groups variance."
10. Defend4 the following statement: "It is misleading to call between groups variance 'treatment variance.'"
11. Explain2 why you should not use t tests to analyze the results of multiple group experiments.
12. There are several terms (all of which end with "variance") for the top part of the F ratio. Name1 those terms.
13. There are several terms (all of which end with "variance") for the bottom part of the F ratio. Name1 those terms.
14. Justify2 the following comment, "if the null hypothesis were true, the F ratio would usually be close to1.0."
15. Explain2 how to use an F table to determine whether an F ratio is statistically significant.
16. You have an experiment with 40 participants and four levels of the independent variable. Calculate3
a. the degrees of freedom for the treatment
b. the total degrees of freedom
17. Describe2 what a statistically significant F for the treatment effect indicates in a multiple-group experiment. State1 two important questions that are not answered by obtaining a significant F for the treatment effect.
18. Contrast4 post hoc t tests with conventional t tests. Defend4 the use of post hoc tests for determining which groups' means differ from one another.
19. State1 the requirements for conducting a valid post hoc trend analysis and explain the implications of those requirements on planning a multiple-group experiment. Then, defend4 the use of post hoc test trend analysis.