Question

Wilfley and colleagues (2008) tested whether the antiobesity drug sibutramine would be an effective treatment for people with binge eating disorder. They measured the frequency of binge eating every 2 weeks for 24 weeks during treatment. The following table lists a portion of the data similar to results reported by the authors for the frequency of binge eating over the first 8 weeks of the drug treatment.

Frequency of Binge Eating

Baseline Week 2 Week 4 Week 6 Week 8.

4 1 0 0 1

6 4 2 0 0

3 0 1 1 0

1 1 0 1 1

2 2 1 1 1

5 1 2 2 2

(a) Complete the F-table. (Round your answers to two decimal places.)

Source of Variation SS. df. MS. Fobt

Between groups ____. ___. ___. ____

Between persons. ____. ___. ____

Within groups (error) ___. ___. ___

Total ___. ___

Make a decision to retain or reject the null hypothesis. (Assume experimentwise alpha equal to 0.05.)

Retain the null hypothesis.

Reject the null hypothesis.

(b) Use the Bonferroni procedure to make the post hoc test. In which week do we first see significant differences compared to baseline?

Week 2 is the first week where significant differences from baseline are evident.

Week 4 is the first week where significant differences from baseline are evident.

Week 6 is the first week where significant differences from baseline are evident.

Week 8 is the first week where significant differences from baseline are evident. None of the weeks are significantly different from the baseline.

Answer 1

a) Applying within group ANOVA:

Source	SS	df	MS	F
between	30.80	4	7.70	6.31
Blocks	12.27	5	2.45	2.01
Error	24.40	20	1.22
Total	67.47	29

Reject the null hypothesis.

Week 4 is the first week where significant differences from baseline are evident.