Persistent patent ductus arteriosus (PDA) is a medical condition that affects more than 40% of very low birth weight infants. Infants with PDA have an increased risk of ailments such as cerebral hemorrhage and bronchopulmonary dysplasia, as well as of death. In a study, Varvarigou et al. (1996) determined that early ibuprofen administration is effective in preventing PDA in preterm neonates. In a sample of 34 such infants, 11 were treated with one dose of ibuprofen, 12 with three doses, and 11 with a saline solution, all treatments beginning within three hours of birth.
As part of the study, clinical factors such as birth weight, gestational age, and one-minute Apgar scores were compared for the three groups. Summary statistics for these variables are presented in the following table.


a. Suppose that an ANOVA is to be performed to compare the average birth weight for the different treatment groups. State precisely the ANOVA model. Is treatment group a fixed-effects factor or a random-effects factor?
b. Using the summary statistics given in the table, determine the ANOVA table for the model in (a).
c. Test whether the three treatment groups differ significantly in mean birth weights.
d-f. Repeat parts (a)-(c) for gestational age.
g-i. Repeat parts (a)-(c) for Apgar score.