1. A manufacturer of infant formula is running an experiment using the standard (control) formula, and two new formulas, A and B. The goal is to boost the immune system in infants. 120 infants in the study are randomly assigned, to each of three groups: group A, group B, and a control group. The study is run for 12 weeks. At the end of the study the variable measured is total IGA (in mg per dl), with higher values being more desirable. We are going to run a one-way ANOVA on this data. A partial ANOVA table is given below.
The mean square for groups in this table is
A. 0.00786.
B. 0.01179.
C. 0.02357.
2. A researcher is studying treatments for agorophobia with panic disorder. The treatments are to be the drug Imipramine at the doses 1.5 mg per kg of body weight and 2.5 mg per kg of body weight. There will also be a control group given a placebo. Thirty patients were randomly divided into three groups of 10 each. One group was assigned to the control, and the other two groups were assigned to each of the two treatments. After 24 weeks of treatment, each of the subject's symptoms were evaluated through a battery of psychological tests, where high scores indicate a lessening of symptoms. Assume the data for the three groups are independent and the data are approximately Normal. The means and standard deviations of the test scores for the three groups are given below.
Multiple comparison procedures are going to be done using the Bonferroni method with α = 0.10. The value of t** is 2.2426. The smallest minimum significant difference (MSD) for finding a difference between groups is computed as 17.68. The correct conclusions from this procedure are:
A. The dose of 2.5 has a higher mean test score than either the control or the dose of 1.5. The control and the dose of 1.5 are indistinguishable.
B. Both treatments have a higher mean test score than the control. The two dose groups are indistinguishable.
C. The dose of 2.5 has a higher mean test score than the control. The two doses are indistinguishable, and the low dose and the control are indistinguishable.