The best painkiller for children. A Washington Post article reported a study comparing the effectiveness of three common painkillers for children. Three hundred children, aged 6 to 17, were randomly assigned to three groups. Group A received a standard dose of ibuprofen. Group B received a standard dose of acetaminophen. Group C received a standard dose of codeine. The youngsters rated their pain on a 100-point scale before and after taking the medicine.

(a) Outline the design of this experiment. You do not need to do the randomization that your design requires.

(b) You read that "the children and physicians were blinded" during the study. What does this mean?

(c) You also read that there was a significantly greater decrease in pain ratings for Group A than for Groups B and C, but there was no significant difference in the decrease of pain ratings for Groups B and C. What does this mean? What does this finding lead you to conclude about the use of ibuprofen as a painkiller?