Suppose a researcher was interested in knowing whether “the combination of nutri
ID: 3241087 • Letter: S
Question
Suppose a researcher was interested in knowing whether “the combination of nutrition and exercise” or an “exercise intervention only” would reduce the weight (kg, after 3 months) compared to no intervention. She presented the following data: Group N Mean (SD) Weight Change (kg) from enrollment to 3 months F-Ratio and p-value Multiple Comparisons Combination Exercise only Combination of nutrition and exercise 15 -6.8 (4.52) F = 12.60 (p=.024) Exercise only 15 -2.3 (2.42) p = .024 No Treatment 15 -0.66 (2.82) p = .036 p = .257
a) What analysis method did the researcher use?
Answer:
b) Which group had the largest mean weight change after three months? What is the evidence?
Answer:
c) Is there any statistical difference in the mean weight change across the groups (at least one comparison)? What is the statistical evidence? Please list all of the statistical differences in mean weight change. Answer:
d) Which of the following statements is true? Bold your answer.
I. There is a significant difference between the “combination of nutrition and exercise” group and the “exercise only” group.
II. There is a significant difference between the “exercise only” group and the “no treatment” group.
III. The “combination of nutrition and exercise” group showed significantly more weight reduction than both other groups.
IV. The “no treatment” group showed significantly less weight reduction than both other groups.
Group
N
Mean (SD)
Weight Change (kg) from enrollment to 3 months
F-Ratio and
p-value
Multiple Comparisons
Combination Exercise only
Combination of nutrition and exercise
15
-6.8 (4.52)
F = 12.60 (p=.024)
Exercise only
15
-2.3 (2.42)
p = .024
No Treatment
15
-0.66 (2.82)
p = .036
p = .257
Group
N
Mean (SD)
Weight Change (kg) from enrollment to 3 months
F-Ratio and
p-value
Multiple Comparisons
Combination Exercise only
Combination of nutrition and exercise
15
-6.8 (4.52)
F = 12.60 (p=.024)
Exercise only
15
-2.3 (2.42)
p = .024
No Treatment
15
-0.66 (2.82)
p = .036
p = .257
Explanation / Answer
a)
The analysis method used is ANOVA in design of experiments, which is basically used to compare more than two treatments at a time.
b)
The group “Combination of nutrition and exercise” has the largest mean weight change after 3 months which is indicated by the smallest p-value(=.024).
c)
The groups “the combination of nutrition and exercise” or an “exercise intervention only” differ significantly as the p-value for multiple comparison test is 0.024
And the groups “the combination of nutrition and exercise” or an “no treatment” also differ significantly as the p-value for multiple comparison test is 0.036.
d)
Which of the following statements is true? Bold your answer.
I. There is a significant difference between the “combination of nutrition and exercise” group and the “exercise only” group.
II. There is a significant difference between the “exercise only” group and the “no treatment” group.
III. The “combination of nutrition and exercise” group showed significantly more weight reduction than both other groups.
IV. The “no treatment” group showed significantly less weight reduction than both other groups.
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