A researcher conducted an experiment on the effects of a new multivitamin on energy level, with a control group (received nothing), a placebo group, and an experimental group (received the multivitamin). An energy inventory that provided a measure of energy level on a 50-point scale was used, where 50 indicated an individual who feels high levels of a lack of energy. The ANOVA summary table follows, together with the mean energy level score for each condition.
|
Source
|
df
|
SS
|
MS
|
F
|
|
Between groups
|
|
1,202.313
|
|
|
|
Within groups
|
|
2118.00
|
|
------
|
|
Total
|
|
3,320.313
|
------
|
------
|
|
Drug Condition
|
Mean
|
N
|
|
Control
|
36.26
|
15
|
|
Placebo
|
33.33
|
15
|
|
Multivitamin
|
24.13
|
15
|
a) Complete the ANOVA summary table.
b) Is fobt significant at a = .05?
c) Perform post hoc comparisons if necessary.
d) What conclusions can be drawn from the F- ratio and the post hoc comparisons?
e) What is the effect size, and what does it mean?