Scenario: Dr. Olson is interested in the effects of three different methods for losing weight in long-distance truck-drivers. He tested a sample of 60 truck drivers. Participants were randomly assigned to one of three groups of 20 people each. Participants in the Diet-Only group followed a low-calorie diet but did not exercise. Participants in the Exercise-only group followed an exercise regimen but did not change their diet. Participants in the Diet + Exercise group followed both a low-calorie diet and an exercise regimen. Dr. Olson measured the number of pounds each individual lost after 6 months.
|
Diet-Only Group
|
Exercise-Only Group
|
Diet+Exercise Group
|
|
5
|
9
|
15
|
|
7
|
10
|
18
|
|
10
|
8
|
20
|
|
10
|
11
|
22
|
|
13
|
3
|
16
|
|
6
|
5
|
18
|
|
5
|
3
|
12
|
|
17
|
10
|
25
|
|
13
|
11
|
20
|
|
11
|
15
|
21
|
|
9
|
9
|
10
|
|
10
|
8
|
15
|
|
7
|
7
|
14
|
|
11
|
14
|
22
|
|
14
|
13
|
21
|
|
12
|
8
|
18
|
|
15
|
6
|
17
|
|
17
|
7
|
23
|
|
18
|
5
|
30
|
|
9
|
12
|
26
|
Questions (Be sure to use complete sentences):
- In this study, what was the independent and dependent variable?
- Describe the center of each distribution: What is the mean for each group?
- Describe the variability in each distribution: What is the standard deviation for each group? What does this measure tell us about the dispersion of scores in each group?
- What would the overall null hypothesis state (in everyday language)?
- What would the overall alternative hypothesis state (in everyday language)?
- Were the results of the ANOVA statistically significant? Explain how you arrived at this decision.
- What was the mean difference between each group? What does this value tell us about the effects of each weight-loss condition compared to the other conditions?
- Were the differences between each group statistically significant, as revealed by the post-hoc tests? Explain how you arrived at your decisions.
- Describe eta2 for this study. What does it tell us about the strength of the relationship between the independent and dependent variables?
- Which of the three weight-loss techniques was most effective; which one was least effective? Explain your answers.
- From all of this information, can you conclude that the different weight-loss techniques caused the truck drivers to lose weight? Explain your answer.