An article entitled "Breast-Feeding Benefits Bolstered" explains that "hospitals were assigned at random to institute a breastfeeding program . . . in which doctors and midwives gave instruction and counseling. The other hospitals . . . provided the usual obstetric care."36 Results showed that "about 9% of the infants who had been in the breast-feeding program had at least one intestinal infection in the first year, compared with about 13% in the control group."
a. Was this a paired or a two-sample study?
b. Was this an observational study or an experiment?
c. Are the results from this study more convincing than those from the study described in the previous exercise because of a larger sample size, because of a bigger difference in percentages acquiring infections for breast-fed versus bottle-fed children, or because of a better study design?