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.